Full Synthetic oil,on a high-ish mileage Gen 3? - Page 2 - Toyota 4Runner Forum

MaineRunna · 02-21-2020, 10:53 PM

Quote:

Originally Posted by Capnemo

I appreciate all the posts but no one really answered the question about whether modern fill synthetic oils tend to leak less.

It is my understanding that once a synthetic (or any) oil has found a way out, changing back will will not stop the new seepage, hence the advice against changing to full synthetic oil late in a vehicles life that has only had dino oil.

I am also not about to try to cure the leaks in this vehicle, it not that brisk but also likely not from just the valve cover gaskets. But if they got worse with a
fully synthetic oil I would be pissed. And seitching back to my current oil, from many reports, would not return to my current leak rate.

It will not cause leaks! Switched to synthetic around 200k and Penzoil Platinum around 224k, no leaks. Most synthetic oil has some conventional oil in in and all conventional oil has some synthetic in it. Replace your valve cover gaskets. Did mine with FelPros 60,000 mile ago, no leaks.

pluton · 02-22-2020, 12:22 AM

Since 1998, I've bought 4 Toyota trucks that had about 100,000 miles on them and then switched them to synthetic. No additional oil leaks have ever occurred.

sawguy50 · 02-22-2020, 09:53 AM

I switched over to Mobil 1 about 2 yrs ago with around 240k miles. I use about a quart in 10,000 miles (not leaking). Change every 10,000 miles with a Wix XP filter. Mobil 1 High Mileage formula 10-30. I do this in all my vehicles with no leaking at all.

brillo_76 · 02-23-2020, 09:20 AM

FWIW.
Like others stated the leaks are caused by warn out seals. Since synthetic is more thinner it can leak out. The benefits of synthetic vs conventional far exceeds the seeps. If the leaks are significant. You could always use 10w-30 synthetic oil until the seals are replaced. Then drop down to 5w -30.

Or run a synthetic and conventional blend.

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