Do you use 15W40 , 10W30 , or even a lighter weight oil ?

Did you use it based on some's recommendation or what the owners manual stated ?

Not asking about Syn-oils , yet............

Some might not agree but I've been using synthetic 15-40 amsoil for past few years, with their filters one factory and one bypass (2micron I think) gota say that it stays cleaner longer, got about 2k on it now and still pretty clear on dip stick. At work we got some big motors with gear boxes and we switched a few years ago to synthetic, we got laser temp gauge and before bearings were at about 200f and now right around 170f plus we change it once a year where before it was twice and it still comes out cleaner.

P.s. one thing I don't like about amsoil is how you got to buy it if you want a good deal.

Dieselfuture, I agree with you on Amsoil  their sales are some what suspect on pricing , the other thing is how their sales people become a instant expert  about oils.

Why is it they must always down other peoples oils ?

Amsoils does not make the base oils they use to blend their product.

I've always wondered how they lay claim to first in synthetics. My grandfather was a mechanic in WWII and has told me stories of the government experimenting with synthetic oils in their military vehicles in Germany. He remembers having to start fires underneath the tanks just to get the oil thinned out enough to get the engines to turn over. They brought in several drums of a synthetic based oil to experiment with on some of the vehicles and even though they still had problems in real cold weather it was a significant difference compared to the convential Oils.

I beleive this is where the claim comes from. "The true milestone came in 1972 when AMSOIL became the first synthetic motor oil in the world to meet American Petroleum Institute service requirements."

Thanks, that makes a lot more sense.

I think filtering oil is as important as weight, plus I wouldn't use newer oils in older engines, they don't have as much zddp and other good things in them because it will plug emission crap on newer trucks. I think that's how it is, read it somewhere before.