Synthetic success stories in high mile engines?

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Oct 11, 2002
Pullman WA
There are numerous posts here discouraging the use of synthetics in higher mileage engines, however, I was wondering if anyone has had good results switching over to synthetics in a higher mileage engine? (100,000+ miles)
hmm my saturn with 160k started leaking oil more and more with synthetic oils. I'm pondering switching permanently to dino oils after my ARX treatment.

Any comments about high mileage engines assumes an engine with age related problems. Like new engines don't have problems with today's synthetics.

Engines that have had to deal with drain intervals that are too long, poor quality oil or are problematic (see Saturn) will likely not like a thinner synthetic oil. They wouldn't like thinner dino oil either.

Those cars have too much engine wear, worn out seals or dirty seals/engines.
I just switched a 1990 BMW 325i with 130k at it to Amsoil 5W-30. It had previously run Halvoline 10W-30 for most of it's life. No leaks yet, though it's probably too early to tell.

Originally posted by mkosem:
hmm my saturn with 160k started leaking oil more and more with synthetic oils. I'm pondering switching permanently to dino oils after my ARX treatment.


If your motor has blowby from stuck rings it will make a seal leak worse from the crankcase pressures-
1989 Pathfinder, 191,000 miles, using synthetics (Amsoil) for 2+ years with no leaks.
1988 Volvo 740 - switched over at 208,000 mi., now has over 248,000 mi. on it with no problems - engine is still dusty dry underneath.

One of the benefits that I have seen is the way that this oil cleans - it took 5 filter changes before I no longer saw crud (gobs of it) in the filter upon inspection! (the fifth one was perfectly clean)
Started using Mobil 1 on both my (98 F-150 & 97 Saturn S-series) vehicles at about 95,000 miles each. Previously had done 3,000 mile changes with Penn 10w-30.

Neither leaked any oil before or after the M1. However, the Saturn consumed about a quart every 3,000. The F-150 has never consumed more than a few ounces of any oil even at 6,000 mile change intervals with M1.

No problems no leaks and they now have 135,000 and 126,000 respectively.

One benefit to the M1 was the Saturns oil consumption dropped to about a quart in 6,000 miles.

Neutra treatment and Schaeffer's 7000 15w-40 has dropped the Saturns consumption to 4oz. in the first 3,000 since switching to the Schaeffers.
is it safe to run a 15w40 in a saturn? I know another guy that's been running 15w40 synthetic on his twin cam and I think he's nuts. What's your take on it?

Haven't seen the numerous posts. But my current daily driver,a 1985 Volvo 245Ti, had about 150,000 miles when I switched, now at 234,000 miles. (prior to this one several other Volvos switched at 150-200K with no issues)
I've used Mobil 1 in eight different vintage Toyotas that I've over over the past 7 years.
They has all run dino oil for 25 years prior to my
changing over to Mobil 1.

No problems with anyone of them. They just kept
running smoother and smoother the longer I ran
them on Mobil 1. And by removing the valve covers
I could see how the Mobil 1 gradually cleaned up their insides.
I switched my 1994 Civic del Sol to 5W-30 Mobil 1 at about 120,000 miles. After 6,000 miles on the initial fill, there was no measurable decrease in the oil level (nor had there ever been before I switched).
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