spark plug heat range

[awthacker]

A neighbor recommended that I go to the next hotter plug than what the engine specs call for, because I am pre-mixing and my oil ratio is rich. Says it may help the engine run more efficient and keep the plugs cleaner from fouling. Do you guys agree?

Also, he recommended I switch from Champion to NGK. Engine is a 1994 Evinrude 175 HP two-stroke. I'd be glad to here anyone's opinion on plugs for this or similar engines.

Thanks,
Aaron