Reader Question: Synthetic Switch?

Here’s the latest reader question, along with my reply!

Glenn asks: Will it cause any problems if I start using a pure synthetic oil in my jeep Patriot, having used regular oil for the last 55,000 miles? I have used regular 5w30 Pennzoil since I bought the Jeep new, the synthetic oil will be the same weight and brand. I have changed my oil and filter religiously every 3,000 miles.

My reply: I highly doubt it.

There are reports of problems in old cars – usually, very old cars – whose owners have switched to synthetic after years (decades) of using non-synthetic. The problems aren’t so much mechanical as visual. The synthetic – which is highly lubricious – seeps past ancient/dry gaskets (e.g., oil pan gaskets, valve cover gaskets) and you get leaks and drips.

Some also report that the synthetic acts like a solvent and causes accumulated gunk in the oil pan to break free and circulate. There is also the fact that many of these old engines – we’re talking 30-plus years old engines – were designed to use conventional oils “back in the day” with characteristics very different from modern oils, synthetic oils especially.

But your Jeep is a modern vehicle and was designed to use modern oil. You have also maintained it scrupulously, so I hugely doubt there is gunk in its oil pan. Synthetic oil will give your engine easier cold starts as it flows well at much colder temperatures than conventional oil; it will also give you better protection under high load/high heat conditions. Both of these attributes will reduce wear over time and should also provide noticeable improvements in driveability and gas mileage. Also, you can extend change intervals to 5,000 or even more – which will offset the higher cost of the synthetic.

PS: Don’t forget to use a high quality filter, such as Wix or Mobil1!

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