M1 in older engine

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May 30, 2002
I use Mobil 1 5w-30 in my '95 Jeep 4.0. Started at 110k miles. Very quiet, better pressures, and no leaks. It did leak a little with Chevron, Pennzoil, and Havoline.???
I'm confused. If you were getting good results with the Syntec, why did you switch?

Did you do any UOAs with Syntec?
Nope, no uoa's at all. Looking through the forum, M1 looks very good for my engine and I can get it at the same price levels. I pretty much don't see any info on USA Syntec, but it appears to thin out.

It could be that I'm just succumbing to opinion.

I don't see any positives here about Syntec.

I'm not sure that it would be productive for me to do the uoa's.
I've went to M1 10-30 in my car. I always ran Castrol Syntec before.

I've also run Syntec in my old truck from about 130K to now 165K with no consumption or leaks. The engine runs much smoother with Syntec, but is noiser with GTX or Havoline. Syntec made it really quiet.

Anyone see any problems with using M1 in this?? I know Syntec is a Group III, but it seems logical if it's staying in M1 should also.

M1 in an older engine will be just fine, I put it in our old 86 Tempo when it had 220,000ish Kms all the way to about 250,000ish kms then sold the car with 257,???kms running Castrol GTX
The easy answer is that they are both good oils. BUT if the M1 makes the motor rattle or something that you don't like go back to the Syntec.

Yes the Syntec thins out some as far as I understand. And just for gee whiz M1 is just thin oil. So I guess it all works out.
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