I am getting ready to change the oil in my '98 Buick LeSabre; 233K miles. I switched to full synthetic two oil changes ago. I am seeing oils; full synthetic, labeled high mileage with the container saying they contain additives that help engines with high mileage. What are these additives and do they offer real benefits to high mileage engines? I am looking at two different full synthetic oils; one states for high mileage engines and the other is just regular full synthetic oil. The price difference is only 25 cents per quart. The engine is still fairly tight; although I do see a significant drop in oil pressure at idle in gear when the engine is hot which I contribute to worn main bearings.

Look at the API rating and if it meets your vehicle requirements it'* good. Extended life or high mileage is a selling gimmick.

In my PK Ave I use 10W-30 synthetic oils.
Besides the API standard, there is now a new standard called ISLAC GF-5 and ILSAC GF-6 generally mentioned on the rear label.
These standards ensure more fuel efficiency and wear protection etc.
Any synthetic oil mentioning (GM'*) DEXOS 1 will be ILSAC GF-6.


I also add a small bottle of LubeGard Bio-Tech Engine Protectant, that significantly reduces oil temps/wear and sure quietens down the valve train big time.

Wait, we're supposed to change the oil?

I sure hope so..Oil & filter ! Pk.Ave oil life monitor is a good thing !

I put over 333 thousand miles on the old 93 LeSabre; when I retired her she had no significant engine issues. Unfortunately, there were a lot of other issues such as suspension and I figured she was getting too old to throw a lot of money in; she also had significant rust on the body and needed a new paint job. The current 98 I have, the original owner wasn't as kind to her. It did have some engine sludge issues when I replaced the lower intake manifold gaskets when I was repairing the upper plenum leak; I wasn't sure they had been replaced or not. I am not planning on replacing the car and want to make sure I maintain her properly. When I replaced the tranny, I put a whole new front suspension under the car; I have the struts to do the rear. I appreciate all opinions; this is why forums such as these are valuable, the wide range of input one gets. Thanks to all that reply.

I agree. It'* mostly a gimmick. My 1997 LeSabre gets full synthetic 10W30 and just turned 250,000 . No engine issues/noises/etc. so far (knock on simulated wood trim). I've had it since 83,000 miles.

Agreed. All this hype about certain oils for high mileage engines is just a gimmick. As long as you change the oil as required, and don't abuse the engine, it will last a long time.