Usually when I think synthetic I think of an oil that is capable of extending oil changes, won't sludge up at 10,000 miles and having excellent winter performance, and keeping things clean among other things.
How long can a group III be run for? I personally wouldn't dare go over 7,500 miles, but I really just don't know anything about group III oils because my main concern with extending oil changes with any dino oil is the possibility of sludge and varnish buildup.
I just want there to be some kind of designation for my oil saying that it is at least comparable to another other of the same class(synthetic), and that if I was running oil X at 10,000 miles, than oil Y will probably be just fine having an oil analysis that isn't catastrophic with a similar mileage.
If I were to use a synthetic such as Amsoil, Mobil 1, GC, and didn't know that a cheap synthetic such as Supertech Synthetic wasn't of the same class and sludged up an engine with 7,500 miles when, say, it was doing just fine with the synthetics at 10,000 miles than where is the destinction of such, thats what bugs me the most about all of this. That is why I wish there was a more standardized way of determining oxidation control because it seems that people are focused on viscosity retention over the period of an oil change, even though it's probably still possible that we can still be leaving sludge and varnish behind at the same time.
I'm thinking maybe we should just have more designation to it, such as Amsoil's 25,000/35,000 mile recommendation and Mobil 1's 15,000 mile designation because to me that means that it won't sludge up if I run it that long and that UOA's will determine within that limit when I should be replacing it.
