engine and drivetrain What oil should I use?

[Guest]

Hey Gang,

I bought a '76 2002 with approx. 125k (so I was told) on the engine. There is no afterrun smoke when I let-off the throttle and the power pulls plenty.

I need to change the oil. The PO told me that he changed it with synthetic 50 weight, made for "high mileage" engines just before I bought the car.

My question, what oil should I be running? What is the recommended oil and weight? I live in Northern CA where I drive the car in 85-105 deg weather in the summer.

Thanks,

Lee

[Chris_B]

I would guess that the PO was referring to a 20-50 weight oil. The "high mileage" thing is a bit of a marketing fiction- all of the features that I have seen associated with this kind of oil would be good for almost any motor, and I suspect are addressed in the additives present in most quality motor oils. Don't know if the "high mileage" oils cost more than the alternative, but 20-50 is probably a good choice for your motor with 125K miles.

Synthetic oils are a good thing for almost any motor, except that they typically are high quality products with excellent detergent additives, so may clean the gunk and carbon out of seals, causing or increasing leaks. The other explanations for this problem (synthetic oils are too thin; they damages seals, etc.) are incorrect.

The question as to whether to go with synthetics is primarily economic (e.g., if your motor has 1XX,XXX miles on it and you intend to rebuild it soon, is it worth spending the substantial extra money for synthetic oil?). One thing is pretty clear- synthetic oils will sustain extended drain intervals. Most manufacturers of this stuff claim reduced wear and friction, but I have never seen a truly scientific study that confirms this. The specs do seem to confirm that they are better for high temp (e.g. turbo or racing) applications... not really that relevant for 02 street service.

[SteveJ]

I have been using Valvoline Racing 20-50 oil in both my 02 and my E30M3 for many years. Changes are done about every 3500 to 4000 miles. Whenever I remember to do it.

My wife has all the newer cars that 'demand' the more costly Mobil 1 or Castrol Syntec. $30 to $50 for an oil change...sheez!

[73touring]

A Good known Brand 20w50 mineral would be my choice. Its the frequiency of changes more than the price of the oil that males a M10 Last. I Change mine every 3k or so or if the oil shows signs of thinning or blackining. I used to use the Duckams 20w50 but cant get hold of it anymore. IN my opinion the rockers seem to like a higher viscosity oil like the 20w50 then 15w40 I definitly notice less valve gear noise and the oil light goes out within 1/2 second.

Rob.

[Napes]

I too use 20/50 in all 3 of out daily-driver ' 02s. But then I live in a fairly warm climate (So.AZ, it was 100º today, 102º yesterday). Winter in International Falls might call for something a little thinner. I generally use Valvoline, but any major brand (QuakerState notwithstanding) is probably OK.

Bob Napier