Is this true of 4 stroke oils? If I change every 5 hours without fail, do you really think the brand matters?No, and yes. If we were talking only about lubing an engine, that would be an entirely different thing. But we have transmission in the mix. Read the link I posted. Some of the most popular auto/commercial oils used by members of this site will barely make it two hours without falling out of grade (wherein your 40wt becomes a 30, or less). What matters is whether the oil was blended to be an engine oil AND a gear lube.