Originally Posted By: BigCahuna
Two things I question in that video. They said using a 10/40 wt oil, over a 10/30 weight oil causes more wear at start up. How can that be? And that heavy oil doesn't dissipate heat as well as a thinner oil. Harley 's been using 20/50 wt oil forever and it seems to work fine . I'm sure they would recommend a lighter oil if they thought it would cool their motors down some. They only recommend 10/40 wt in the winter when temps are under 40f.So I'm not buying what their selling.,,
A 10w40 is thicker than a 10w30 at the same temperature. The 40 grade gets its 10w rating at a warmer temperature than the 10w30.
Thinner oil does cool better, there's no denying that. The Harley needs 20w50 since it doesn't have water cooling to keep the temperature in check it will always run a hotter oil temperature than a water cooled engine.
Two things I question in that video. They said using a 10/40 wt oil, over a 10/30 weight oil causes more wear at start up. How can that be? And that heavy oil doesn't dissipate heat as well as a thinner oil. Harley 's been using 20/50 wt oil forever and it seems to work fine . I'm sure they would recommend a lighter oil if they thought it would cool their motors down some. They only recommend 10/40 wt in the winter when temps are under 40f.So I'm not buying what their selling.,,
A 10w40 is thicker than a 10w30 at the same temperature. The 40 grade gets its 10w rating at a warmer temperature than the 10w30.
Thinner oil does cool better, there's no denying that. The Harley needs 20w50 since it doesn't have water cooling to keep the temperature in check it will always run a hotter oil temperature than a water cooled engine.