Check Before Your Pour … and Before You Fill!

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The other day, I changed the oil/filter in one of my old cars. Because I have a small fleet of antique vehicles, as well as several “daily drivers” (plus a lot of equipment, including a tractor, riding mower, generator – you get the drift) that also need their oil/filters changed periodically, it is easy to lose track of which gets what – and most of all, how much.oil change lead

The old car, for instance. It’s an old Pontiac (’76 Trans Am). I know – because I am an old Pontiac guy – that all classic Pontiac V-8s (the 455, as in my car, bu also the 428, the 400, the 350 and the 326) take not the usual five quarts of oil that most American V-8s need but six. A person not into Pontiacs – or knowledgeable out them – or lacking a service manual – could easily make the mistake of under-filling the crankcase. Oil is important. You want enough of it inside your engine.

And, the reverse.

My four cylinder pick-up trucks only take a bit more than four quarts. Overfilling can be worse than underfilling the crankcase – but either can lead to troubles easily avoided by being sure to check before you pour.

And, measure before you pour. 5 quart oil jug pictures

It’s pretty common today for oil to be sold in five quart jugs. But what if – as in the case of my Nissan pick-ups – you need 4.2 quarts? Some jugs have marker lines, but some don’t – and sometimes, the gradations are not very precise. To be sure, you can measure out the oil into a beaker – or use a quart bottle.

And, if you don’t do your own oil changes, be sure to check the work of whoever does. At most oil change joints, they do not pour the oil in a quart at a time. They use a gun that meters out “x” quantity from a 50 gallon drum. It is not uncommon for the guy wielding the gun to over (or under) fill the crankcase. Which is why the first thing you ought to do after getting your keys back is pop the hood and pull out the dipstick. Be sure it’s right before you drive away.

Here’s another – tire air pressure.

If you own several vehicles – especially if some are much older and some much newer – you will discover (or may already know) that tire pressure recommendations can vary a lot from one vehicle to another. For one thing, the old 28-32 psi rule that used to be a good rule of thumb for most cars does not apply anymore. Some of the new cars I test drive recommend 40 psi – or even more. Thus, 32 psi would be significantly under-inflated, and your car’s handling would be sloppier, its braking distances longer – and its gas consumption higher. On top of all that, the tires will wear faster, too.air pressure picture

Then there are old cars – and motorcycles – if you have ‘em. One of my old bikes (40 years old now) wants no more than 28 pounds. But the more modern sport bike likes 35. As anyone who rides will tell you, inflation pressures are even more crucial on two wheels than on four. Drastic differences in handling – the kind you don’t want – can happen if you’ve put too much or tool little air in your tubes. Speaking of which. Bike tires seem (to me at least) to be more prone to leakage than do car tires. It may be due to the fact that virtually every car tire is a tubeless radial – while many bike tires still use tubes. But, regardless – and especially if the bike sits for days/weeks at a time – they seem to lose air faster than car tires. Given the potentially negative consequences of low inflation pressure, it’s a wise man who always checks the tires before he rides. With a car, it’s usually ok to do it every couple of weeks – unless you’ve got a known “leaker” – one tire that seems to lose air faster than the others. In which case, do it more often – and maybe take that wheel/tire in for a look-see. It might not be the tire, you see. Modern car wheels are often aluminum alloy wheels – and sometimes, during the casting process, imperfections happen that can’t be seen by the eye but nonetheless result in aggravating minor leaks, no matter what you do to the tire.AC recharge picture

Air conditioners. Some of my stuff is pre-1990s – and so, the refrigerant in the AC systems is R-12 (Freon). Not the current R134a stuff. Most cars made after about 1995 or so use 134a – and while it’s not easy (because it’s not legal) for the average person to get hold of a can of Freon, anyone can buy a can of 134a – and a recharge kit – at any car parts place. This is great – if the system you’re about to recharge is a 134a-compatible system. But if it’s not . . . you most definitely do not want to stuff it full of 134a. Because if you do, the result could be major expensive damage to the system. (I’ve read and heard about people using 134a in R-12 systems without trouble, but the recommended procedure is to thoroughly evacuate the R-12 refrigerant and purge the lines before adding 134a. Mixing these two refrigerants and their lubricating oils is a bad idea.)AC recharge gauge

Also, if you’re going to attempt the DIY AC system recharge with one of those kits, spring for a kit with a gauge that indicates when the system is charged – and which will prevent you from overcharging it. Just as is true of engine oil, too much refrigerant (and pressure) is as undesirable as too little.

All the foregoing is the mechanic’s equivalent of the carpenter’s measure twice – cut once.

Words to live by – and wrench by!

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  60 comments for “Check Before Your Pour … and Before You Fill!

  1. Joe
    September 18, 2013 at 9:59 am

    Being off by as much as a quart will probably not hurt any engine. I had a Nissan sentra that was 4 qrts but didn’t see that amount until after 2 years of doing my usual 5 qrt oil change. My Toyota Rav4 is 6 qrts yet after putting in 5 qrts the difference on the dipstick was negligible. Everything also depends if you also change the filter and the amount of time you allow the oil to drain. As far as the A/C refrigerant goes I have no idea. Years ago when I drove older cars and my A/C died I just sucked on an ice cube :-)

    • DownshiftFast5to1
      September 18, 2013 at 11:10 am

      Joe, YMMV, however; quite a number of mechanics have told me that overfilling the crankcase with oil leads to gasket failure.
      It takes time to develop. How much? I don’t know.

      I imagine there’s other problems that result too, depending on the engine type.

      If being over or under wasn’t important, why would the manufacturers put lines on the dip stick?

      • BrentP
        September 18, 2013 at 11:33 am

        Overfilling should do nothing until the point where the crank shaft dips into the oil. at that point it foams up the oil and results in a loss of lubrication.

        If the level of the oil is above the oil pan gasket and the gasket wasn’t designed for it, then it may leak, but the solution is to go back to the proper oil level.

      • Joe
        September 18, 2013 at 2:14 pm

        Adding the right amount and correct type is important. You are correct in that the damage may take some time to develop but I just never experienced anything. After 200,000 miles a car is pretty shot anyway. Yes people can get 300,000 miles on an engine but with the engine only being one aspect what can disable a car I would say exact measurement/oil type is not extremely important…just important. Of all the cars I’ve owned only one car was scrapped because of engine (burning more oil than gas) failure.

        • DownshiftFast5to1
          September 18, 2013 at 2:27 pm

          “After 200,000 miles a car is pretty shot anyway. ”

          Uh, yeah, ok. If you say so.

          • Tor Minotaur
            September 19, 2013 at 4:00 am

            I always listen to the ruling class, old goes out of style, new things always come into fashion, and you have to keep up. Cars, clothes, you name it, out with the old and in with the new, that’s what keeps America great.

            That’s why I buy a new house every 3 years with a 3 year mortgage. On the day I make the last payment, I burn that outdated house to the ground, so I can get me a new one. I just love that new house smell, and also getting all the mortgage interest deductions on my taxes.

          • Garysco
            September 19, 2013 at 4:08 am

            Downshift – Stop it. My Geo just crested 200K and I am just now thinking about a new engine & trans for under $2,000.00. But on the other hand if it dies tomorrow I will just pull the plates and kick it to the side of the road and let the Highway Patrol deal with it.

          • DownshiftFast5to1
            September 19, 2013 at 5:12 am

            Garysco, just today I was thinking as I drove my ’94 (with the window cranks and no airbags, TYVM EPA for the idea) the one I sunk wayy too much into, that it’s not exactly whatchya would call a ‘sleeper’,… but it’s mechanically solid.
            And the car thieves won’t look at it twice, or even once.
            The spray paint vandals might even pass it up.
            And surely the cops won’t look at it as something they’d want to asset forfeiture.
            Suddenly, it had more value than before, and I don’t want to get rid of it. I plan on 350,000. So unlike my last vehicle I won’t be entertaining the thought of tossing it to the side of the road like you do now. But of course, your tune will change if you get that new motor and tranny.

            Also, Tor, You’re sooo Thehousingbubbleblog, it’s not even funny. …Well, maybe a little.

          • Garysco
            September 19, 2013 at 5:23 am

            Maybe I picked up a bad attitude working in a jail.” When ya ain’t got nothing, ya got nothing to loose.” I have though about that attitude many times. Kind of sets ones mind free after a fashion. Especially as I look at the leased BMW’s and Mercedes go down the road with unhappy looking drivers behind the wheel.

          • DownshiftFast5to1
            September 19, 2013 at 5:47 am

            “working in a jail” – Now there’s a scary thought.

            Anyway, RE: “Kind of sets ones mind free after a fashion.”

            You got that part right.

            Heck, for the most part I don’t have to worry about locking my doors. It’s quite liberating.
            The only time I lock my doors is when I leave more than $100 worth of stuff in it, because then, the cost of replacing the broken window is lower than the stuff I risk.
            …Maybe not even then, replacing a window is a bitch.

          • Garysco
            September 19, 2013 at 6:00 am

            @Downshift See. Jail is a great paid education on human nature while living with them in a fish bowl. There are all types there, and they don’t change their MO just because they are locked up.

            I sort of misquoted my thoughts. More like a mix of what I said and Janice Joplin: “freedom is just another word for nothing left to loose”. As long as I have enough to be warm on a cold night, fed well, an air conditioner on hot summer days, and to be as far away from clovers as possible. It must have something to do with my passion for motorcycle touring. Now that I would hate to loose.

        • September 18, 2013 at 2:54 pm

          Hi Joe,

          A great deal depends on the particular vehicle. I can tell you that, for example, Toyota had lots of problems with its 3 liter V-6 when the crankcase was overfilled. And while under-filling the crankcase may not cause obvious, immediate problems – the engine will likely experience higher operating temperatures (remember, oil is there to cool as well as lubricate) as well as increased wear and tear from the increased operating temperature and the high concentration per volume of contaminants held in suspension in the oil itself.

          • Garysco
            September 18, 2013 at 3:03 pm

            Eric, maybe newer engines are different. But overfilling would blowout the seals and such from over pressure and crankshaft slapping the stuff in the crankcase?

          • September 18, 2013 at 4:16 pm

            I think it depends on the specific engine. I’ve read that that emissions systems (crankcase ventilation systems especially) can be bolixed up by too much oil in the system – and my guess (based on what I know about the way new engines tend to be designed, for packaging reasons) is that there’s not a lot of excess capacity designed in. That is, the oil pan/sump is designed to take “x” amount of oil – and very little more. Put more in, and the crankshaft is gonna be whipping it up into froth, you’re gonna get blow-by… and problems!

    • DownshiftFast5to1
      September 18, 2013 at 11:38 am

      Another example I just thought of, on some Toyota’s, oil affects the timing chain tensioner, without enough oil, premature failure occurs.

      Some experts claim it even matters what type of oil filter you use. One expert that I know claims a person should Only use the Toyota brand oil filter to provide sufficient oil pressure to the timing chain tensioner.
      Is he right? I don’t know, but with forty years of racing and engine building experience, I defer to that.

      Many 4×4 enthusiasts claim that only certain brands of oil filters have a flap in them that prevents the oil from running back out and staving the engine. Being low a quart or two wouldn’t help things either in certain situations, i.e. steep grades. How steep? I don’t know.

  2. Garysco
    September 18, 2013 at 10:39 am

    I have ruined two different motorcycle tires in less then 500 miles because they ran a little to low causing cupping & uneven wear. Lesson learned.

    • September 18, 2013 at 10:44 am

      Been there/done that, too!

      It’s a lesson you’ll hopefully only have to learn once.

    • ЯΞ√ΩLUT↑☼N
      September 22, 2013 at 6:13 am

      I’ve ruined motorbike tyres by using too light a grade of fork oil. Pressure depends more on the tyre itself regarding brand and type. I reckon that bike tyres go flat faster than car tyres is because there’s far less volume in them to begin with. I have to top mine up every week.

  3. Doug
    September 18, 2013 at 11:07 am

    Why is it, there always seems to be more oil going into the motor than is drained out? This has been a consistent phenomenon with me ever since I made my first oil change on my Parent’s ’63 VW.

    • September 18, 2013 at 11:43 am

      Hi Doug,

      Many (most) engines consume a little oil as they operate. So, if you put in say 5 quarts six months ago and find that, today, only about 4.5 drained out, it’s probably the result of normal usage over time.

      • Doug
        September 18, 2013 at 2:05 pm

        I knew you would say that. I fill all my cars to the maximum on the dipstick. If I were to burn ,25 – ,5 Liters, it would be reflected on the stick. It is not. Two years ago, I drained and filled to the maximum, the oil on one of my cars. I drove it for only about 1500Km (that’s about 900 Miles in US only speak), stored it from September to May and the usual thing happened. When I changed the oil, the amount of oil coming out of the containers was less than the amount of old oil I filled them with – this includes the oil from the filter. Not a huge amount but measurable.
        I understand not all the old oil comes out but whatever comes out should equal what goes in. The only thing I can guess is, maybe the containers have slightly less than one Liter of new oil.

        • Doug
          September 18, 2013 at 2:24 pm

          Wait a minute! That doesn’t make any sense – unless the NEW containers had less than one Liter – but that would be a one-time thing. I don’t drop/spill/swallow/sop-up with my shirt that much oil.

        • September 18, 2013 at 2:34 pm

          Hi Doug,

          Dipsticks can be inaccurate. Many are press-fit (the tube, at any rate) and if not installed quite right, the reading you get on the dipstick could appear to be off even though the actual level is ok.

          If you put a given known volume in – and are seeing less come out – then some of the oil is being lost, either through combustion or leakage.

  4. September 18, 2013 at 12:43 pm

    My late husband was a professional machinist, but not a mechanic. He spent a good part of his adult life on an aircraft carrier, and much of his time before that on a horse as a Texas cowboy… But he was willing as a new day. So, early in our marriage, he decided to change the oil in my little Honda car. After draining out the “old oil,” he found that the “dip stick” still showed the pan full of dirty oil. Unwilling to mess with it any further (I wasn’t home at the time), he drove his car to the service station down the road for a little consultation. Seems he’d drained the manual transmission instead of the oil pan. So glad he figured that out… and I never even teased him about not noticing the oil FILTER sitting right in front of his eyeballs when under the car. LOL I had been married to a regular mechanic for 17 years before that, and always changed my own oil, etc.

    Guess who got that job back right away. :)

    • September 18, 2013 at 2:45 pm

      Good thing it wasn’t an automatic… because he’d never have made it out of the garage!

      Probably, you could drive a vehicle with a manual gearbox that had been emptied of gear lube a good distance before heat and friction began to seal its doom (residual oil on the gears providing some protection, I suppose). But an automatic drained would not even give you positive engagement in “Drive” – and would burn up almost immediately.

      • September 19, 2013 at 9:46 am

        Yes, but I’m glad he used HIS CAR to drive to the station, leaving mine on the ramps. :) He wasn’t a mechanic, but he was a great guy anyway. LOL

        • September 19, 2013 at 1:23 pm

          True Story:

          One of the people employed as a driver for one of the press fleets – the people who bring new cars to journalists to evaluate – managed to put 10 gallons of unleaded premium into a diesel Audi. With foot-high CLEAN DIESEL billboard lettering on either flank.

          I gather it cost a tidy sum to purge the poor Audi….

          • September 23, 2013 at 6:11 am

            I have somewhere heard that that’s such a serious issue for rocket fuels (especially for hypergolic bipropellants that ignite when they mix) that the operators use special fittings that only mate the right containers together.

          • Uwe
            October 6, 2013 at 9:07 am

            I suspect there was a lot more involved than just purging it. If it was run at all after putting gasoline in the tank, I bet the high pressure fuel pump got trashed and that would leave little bits of metal all throughout the fuel system. That’s an inherent weakness in modern, common-rail injected diesels; those high pressure pumps produce 20,000-30,000 psi of fuel pressure and are very unforgiving of any contamination or mis-fueling. When that pump fails, the usual repair is to rip and and replace most of the fuel system, including the rail(s), the injectors, and lots of other parts. People have gotten bills as high as $8-10k for such a repair and that was on the 4-cylinder cars. If this was a V6, I’d bet $10k as an absolute minimum.

      • September 23, 2013 at 6:05 am

        It depends on the kind of automatic transmission. I’m not sure how a belt automatic transmission would cope, but it certainly doesn’t use a fluid based torque converter (and I would really like to see some Constantinesco mechanical torque converters around, now that we have metal fatigue resistant alloys to make the sprags out of and now we know to use V grooves to engage the sprags better; I think you could get a rather nice retro system that would be simple if not quite automatic, with one of those torque converters between the engine and a two-forward-one-reverse pedal operated model T Ford style epicyclic gearbox).

      • Steve
        September 23, 2013 at 8:48 am

        He was working on her car, but drove his car in for consultation. And good thing, too, as you pointed out.

  5. Ferret
    September 18, 2013 at 12:45 pm

    I normally keep extra oil and filters around for when it’s oil change time and so I don’t have to stand in line at VatoZone, waiting behind dozens of Cletii feel competent enough to swap an alternator but have no idea if their car is a V6 or V8.

    Years ago, I had a roommate who was (much) less mechanically inclined than the aforementioned Cletii. One Monday morning, he started up his (old and busted) Protege and the thing was just puking smoke from the tailpipe. He drove it to work anyway and took it to a nearby shop to get it checked. That evening, I asked if they found the problem. He said they told him there was too much oil in it. When I asked how much he had put in, my jaw hit the ground with a ‘thud’ as he said he filled it to the top.

    Of course, it was only several weeks later when I went to change my oil that I discovered one of my cases of oil was filled with empty bottles.

    • September 18, 2013 at 2:42 pm

      “… my jaw hit the ground with a ‘thud’ as he said he filled it to the top.”

      Just pissed myself laughing… thanks, Ferret!

    • DownshiftFast5to1
      September 18, 2013 at 9:48 pm

      That’s weird, I think I repaired that guys snowblower today.
      You couldn’t fit another drop into that thing if you tried, it was so overfilled.

      “It wouldn’t start. …Oil was sputtering out the muffler.”

      Oil fouled plug, plus incorrect starting procedures.

      I don’t want to tell him the reason.

      • Jean
        September 19, 2013 at 2:47 pm

        Ya know…
        Makes me wonder.
        My parents have (?) a Honda lawnmower. Nice model, when Honda still made good stuff. Anyway – I remember mowing, and it was a steep grade, but still… I always wondered about the oil sputtering out of the exhaust (happened only ONE season, but still…)

        Guess I know now. ;-)

        • DownshiftFast5to1
          September 21, 2013 at 4:22 am

          Ya, on steep grades, use Only an old two stroke Lawnboy (the ones they’re not ‘allowed’ to make anymore) or one of the newer and quite expensive Honda four strokes.
          Otherwise, you’ll starve the engine of oil and end it’s life right quick.

          And oh boy are those regulations making those old Lawnboys maintain a high price.
          Even the junk ones for parts.
          …It’s ridiculous.

          Hmph, it’s kind of like a Cash-For-Clunkers for lawnmowers.

          But it sounds like you have no steep hills to mow, and that’s a good thing. Ha. ….Pity the poor souls who do, eh?

          They should just get goats!
          … If Only The City would let them.
          …And chickens too.

          • September 23, 2013 at 6:18 am

            There’s a trick you can use with rabbits: have a hutch with a wire mesh bottom and slightly raised wheels at one end so you can wheel barrow it but still put the bottom down flush, then move it around where you need it.

          • DownshiftFast5to1
            September 24, 2013 at 6:45 pm

            I like that idea, P.M.Lawrence.

            If it had chickens in it, they’d call it a chicken tractor.
            I guess that makes it a rabbit tractor?

  6. GW
    September 19, 2013 at 8:23 am

    Eric – I have a question regarding tire pressure…

    I have heard from various mechanics and other that the tire pressure should always be kept at the CAR Mfgr’s recommendations.

    So when the TIRE Mfgrs has a different recommended pressure – how does one rectify this conflict?

    • September 19, 2013 at 8:47 am

      Hi GW,

      The car MFGR lists a specified pressure that assumes the OE (factory equipped) tires. If you stay with that brand/type of tire, then I’d stay with that recommended pressure.

      However, it’s common for people to change brands (and more importantly, other parameters; for example, a more aggressive “sport” tire vs. the OE all-season) and in that case, I’d be inclined to go with the tire MFGR’s recommended inflation pressures.

      I have a personal example I can relate.

      I used to own a ’64 Corvair. I put a set of modern radials on it. It originally came with bias-plys. I did not stay with the original inflation recommendations, because the tires were very different in their design. I had to fiddle with it some to get the right pressure (very big issue with the Corvair) but the final number was not what the factory recommended.

  7. Frank
    September 23, 2013 at 12:30 am

    Eric, you mentioned Nissans requiring “odd” quantities of oil. The V6 in my Murano takes 4.1 quarts. That’s bad enough, but another endearing characteristic of Nissan V6 engines is their dipsticks. Instead of going into the oil sump directly, Nissan routes the dipstick through the block – which results in erroneously high readings on startup or just after the engine has been run. To get an accurate dipstick reading, run the engine for a minute or so, shut it off and wait a few minutes before checking the dipstick. This will give the oil time to settle back into the sump. Auto techs know this but customers, by and large, don’t.

    • September 23, 2013 at 5:32 am

      Thanks for the heads up on that, Frank – good to know!

      Does Nissan make mention of this in the owner’s manual for your Murano?

      They ought to!

  8. September 23, 2013 at 6:20 am

    According to https://en.wikipedia.org/wiki/Dichlorodifluoromethane: “R-414A is designed as a drop-in replacement (substitute) for R-12″.

    Also, non-U.S. readers should remember that the U.S.A. devalued its fluid measures; pints, quarts, gallons etc. there are 20% smaller than the real things.

    • Bob S
      September 23, 2013 at 4:17 pm

      Huh? When did they do that?
      How come they didn’t tell anybody about it?
      They did?

  9. Joel
    September 23, 2013 at 6:58 am

    Motorcycle tires lose air more rapidly because they have much more surface area per volume of air.

  10. charlie
    September 23, 2013 at 1:09 pm

    Running tires at 32-35 is BS. When run that low the outer tread wears out faster than middle tread. I run my tires at 40+. They wear more evenly and longer, and I get much better gas mileage.

    • Ed
      September 23, 2013 at 1:20 pm

      Yep, the manual calls for 34psi on my car. Running the manufacturer’s recommended tire, I inflate to 37.5 in the summer and 40 in the winter. Better mileage, great handling, and much more even tread wear.

    • Eightsouthman
      September 23, 2013 at 1:39 pm

      My wife’s car has tires with a 44 psi max. I found out just through use that 42.5 front and 38 rear worked well. Speaking of which, we just had a big cold front that’s dropped our daily highs by 15-20 °. I need to go add air to the entire set. It’s a good idea to add air every month and when temperatures change. When I worked my one ton all the time I constantly raised and lowered the tire pressure for the load. I once had a source of free nitrogen and it was the nads for use in tires, wish I still had it.

  11. September 23, 2013 at 1:31 pm

    You mention the obscure Pontiac 350 V-8 but not the 389 or the 421?!? Scandalous. That 389 was in a vast majority of early to mid-60′s V-8 Pontiacs (ever heard of the original GTO?) and the 421 Super Duty ruled the roost in NASCAR and at the drag strip in 61, 62. and 63.

    All Pontiacs V-8 engines from the the 1955 271 to the 455 shared the same size block, the big displacement engines (421 and above) added larger main bearing journals in 1961.

    • September 23, 2013 at 1:53 pm

      Roger all that, James – good to hear from a fellow Pontiac fan!

  12. john bear
    September 23, 2013 at 5:06 pm

    ? 1. Is it better to use synthetic oil? 2. Is it better to drain the oil with the engine hot?

    • September 23, 2013 at 5:19 pm

      Hi John,

      Lots of opinions on this; I’ll give you mine:

      If we are talking about a vehicle not subjected to extremes, such as very high heat, or extreme cold – or high-performance use – if you stick with a name brand conventional oil that meets the manufacturer’s minimum service specifications, you’ll probably have no troubles.

      But in a vehicle that sees extremes – very high heat/very cold, or which is driven in a high-performance manner – the additional protection a synthetic provides at the margins (e.g., when the engine is being run hard in high heat, for extended periods) is worth the extra cost.

      Synthetics will also often provide a slight but noticeable uptick in both driveability and gas mileage.

      I use nothing but synthetics in my old muscle car, my air-cooled antique motorcycles and my high-performance sport bike. But I use a good quality conventional oil in the pick-up.

      Hope this helps!

      • john bear
        September 24, 2013 at 3:18 pm

        Thanks. But what about changing the oil when it’s hot. Seems to me that this would help get sludge out of the crankcase.

        • September 24, 2013 at 5:44 pm

          Hi John,

          You should always try to change the oil after having fully warmed up the engine – for exactly that reason.

          I can tell you, though, that sludge accumulation is not likely to occur if one performs regular oil changes with good quality oil, synthetic or conventional. Modern engines run near-ideal air-fuel ratios and there is far less contamination of the crankcase (assuming the engine is in good mechanical condition).

          This has been my experience, anyhow, opening up the engines in my various vehicles!

  13. tom
    September 23, 2013 at 5:10 pm

    Also w/automatic transmission fluid changes, the capacity is determined by if you drain the torque converter or not. On my 98 Econoline van, the pan and filter is about 5qts, but the torque converter is another 9! I drain it then put it into empty milk jugs to get a reading, then refill using that number. Fine tune it with the dipstick after driving it around the neighborhood. Automatics are very particular about how much fluid is in there… too little and they wont shift!

    • September 23, 2013 at 5:20 pm

      Indeed, Tom!

      Thanks for bringing up a very good point.

      You can also burn up an automatic by running it with too little fluid, so it’s extremely important to fill to the correct level.

  14. Darrencardinal
    September 24, 2013 at 1:34 am

    I was interested in the comments about tire pressure.

    I drive a Miata and Mazda recommends 26 psi on all 4 tires. This seems really low compared to some other cars, anyone know why they would set it so low?

    Would there be any benefits from going higher?

    • DownshiftFast5to1
      September 24, 2013 at 2:44 am

      Darrencardinal asked, “Would there be any benefits from going higher?”

      I’m guessing, better mileage?

      Or course (I’m guessing) that would be at the expense of longer tire life and less traction.

      I’m a 4×4 guy, so i think you should cut out the wheel wells and put on wayy oversized tires, add a snorkel, maybe put on a brush guard, then you’d be set.

      Ha! I’m just kidding, except the first part.

    • DownshiftFast5to1
      September 24, 2013 at 2:56 am

      Ooops, I’m just kidding, Except About The First Two Parts.

      I’ve heard a great many good things about that car.
      I’d like to get my hands on one.

      …Me, a Miata, and an open gravel road. …Oh that sounds like FUN!

      No, seriously, I’d stay with the Mazda recommendations, or the tire manufacturer recommendations. Unless, of course, you wanna do some muddin’?
      …But I’m just some guy, maybe the experts will weigh in?

    • September 24, 2013 at 6:59 am

      Hi Darren,

      Keep in mind those pressures assume the stock wheel/tire combo (and perhaps also the suspension your car’s got – either the base or the more aggressive “sport” settings, etc.).

      If you change tires, or alter the suspension, a different pressure may be needed.

      As a rule, the car manufacturer recommends a given psi to balance ride quality, handling, and wear. Sometimes, you can improve handling by increasing the pressure – at the price of a rougher ride/faster wear.

      I’ve found with cars like the Miata – a sports car lots of people modify/race – that it’s helpful to check into what others have done to their cars, get their results – and use the info to decide what to do with your car.

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