There is the government to thank for that.If you have statistics that prove it please provide. The only thing I've seen from Japan is a massive amount of imported late model rebuilt engines for sale on eBay. Thousands of them.Originally Posted By: bubbajoe_2112Yep, and don't forget that Honda has been running 0W20 in Japan since 2001 with no issues...Originally Posted By: DanhWe have a real-world, large number comparison of 5w/20 vs 5w/30 longevity going on right now: Ford vs GM. Ford has recommended 5w/20 for at least a decade while GM continues with 5w/30. If 5w/20 really shortened engine life by 30%, don't you think Ford would be suffering in comparison to GM? It seems to me there is no real perceived difference in engine longevity between the two. The bottom line seems to be that 5w/20 allows an engine to last every bit as long as 5w/30 if the engine was designed with it in mind. Also, let's not forget that a disproportinate amount of wear occurs on cold start-ups, where a lighter grade of oil is helpful. But as others have said, if you feel beter going "thicker", have at it.