The factory original oil light switch turns on at 7 PSI, so there are lot of engines running around with almost no oil pressure at hot idle. Unless the light starts to flicker, most people don't realize just how low pressure can go and still keep the engine lubricated. What's the pressure at full temperature and 2K RPM? If it's at or above 30 PSI at cruise speed, you probably don't have much of a problem. Try running 15W-40 oil, or straight 30 weight HD oil. DO NOT run 30 weight non-detergent- - - -it's not rated for anything with an internal combustion engine any more- - - -including lawn mowers!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!