Penn Grade 20-50

PG1 motorcycl oil is recommended for bikes that share a sump with the clutch and transmission. My 2012 Road King does not. I’m thinking that their High Performance Partial Synthetic 20-50 would be a better choice. Bike has an oil cooler and I have an aftermarket oil pan that increases capacity by almost 1 1/2 quarts. any thoughts?
Colorado, USA
With respect to your non-shared sump engine, heat can play a factor (vs shearing from a shared sump) in the oil staying in grade to some extent even with an oil cooler. It’s going to help, so you could try both and see what analysis shows. With that much extra capacity and a cooler, is it possible the oil might not get up to temperature when ambient temperatures are not extreme? Either one’s gonna be a good oil, however I wouldn’t say the semi synthetic is a better choice, it’s just another choice you could make.

A good synthetic will shear less relative to a good conventional of the same weight. Compared both 20w50 synthetic to conventional and 10w40 synthetic to conventional and it’s not even close in my shared sump ZRX1200 with respect to staying in grade based on analysis. Which also equates to shift quality staying consistent versus falling off within a couple thousand miles.

If I made a suggestion, my thought would be the synthetic would hold up better (stay in grade) compared to a semi synthetic with respect to an air/oil cooled non shared sump engine and longer OCI’s. Don’t know what OCI you plan, however if you are doing them at 2000-2500 miles it’s a moot point. When you extend it out is where the synthetic will have a definite advantage, IMO.
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harleys run hot + better oil is good + hopefully your oil cooler is temperature controlled! i always run REAL synthetic oils in my bikes as it helps cooling as well as many other benefits. your location could help as oil selections + ambient temps effect safer choices