Yamaha manual for my motor states 10w30. Distributor says 10w30 for "northerners" and 20w40 for "southerners," per Yamaha's recommendation. Short of trying to call Yamaha direct, has anyone heard of this supposed change by Yamaha?
The Yamalube web site shows both products, but doesn't show the applications. Written specifications in my Owner's Manual would be good enough for me. But, if I was still curious I would spend the nickle and 5 minutes of my time and call their toll free number and have the experts tell me.
In your owners manual is a temperature graph to show what grades of oil to use over several operating temp ranges. 20W-40 is acceptable for summertime temperatures.
Tropical areas use 20w-40 and all others use 10w-30. Most of my commercial guys use the 20w-40 while recreational boats use 10w-30 and I'll sell 10 cases of 10w-30 to every 1 case of 20w-40 sold.
