Originally Posted By: Pablo
I want to see these studies that show any 0W-20 prevents wear better than any other 0W-20. Amsoil can't claim it - but other oils can? The argument goes along the lines of the thinner the better at start, and some amount of wear is at start up, therefor the thinner the better. I content any 0W-20 is plenty "thin" enough at start.
"thin enough" for what, though? For almost all conditions, any generic SM or SN 5W20 will provide "enough" protection for any engine for which it's spec'd. If your standard is "good enough", then Amsoil's entire product line would be obsolete, wouldn't it?
A disproportionate amount of wear happens at start-up and until the engine is up to operating temperatures. Oils which are thinner at start-up will pump more easily, at lower pressure, and get up to operating temperature more quickly. Therefore, it's really not too difficult for me to theorize that an oil that is thinner at startup is going to have less wear over the service life of an engine.
Obviously, oil viscosity isn't the only cause of start-up wear--deformation of the cylinder walls and pistons being another. But still, I really don't need an extensive study to convince me when I can simply look at the mechanisms in place that cause "wear". I'm also not of the myopic view that bearing wear is the only parameter of concern. I'm much more concerned about things that actually matter, such as wear at the valve stem seals, cam and main seals. Lower oil pressure over the life of the engine can't help but have a positive effect on the performance of these seals over the long-term. It's been demonstrated in SAE testing, and it's also a matter of simple physics--the lightest oil which doesn't leak creates the least amount of wear on an engine oil seal.
Sure, it would be nice for Toyota to do a protracted test to show that their oil is "better", but they're in the business of selling cars, not oil--so I'm not really holding my breath. But in the meantime, I'm going to look at the mechanisms that cause wear, and use my own noggin to pick an oil--and for me, the oil which a)meets my mfg specifications, b)is reasonably-priced and c)lightest at start-up is going to be the oil that gets the nod. But I also never lose sight of the fact that any certified oil (which actually meets the specs for which it claims) is "good enough". Then again, if "good enough" is the standard, there's not much sense in even having this forum.
