I just purchased a 3000 mile pre-owned '21 Himalayan (413cc air cooled single cylinder thumper with air to oil cooler). The manual states to use synthetic blend 15W50. About two years ago I bought a bunch of the Delvac 1 ESP 5W40 full synthetic that were on sale with big rebates (I think they ended up being about 10 bucks a gallon) and I have at least 8 gallons left. I use that oil in all of my small engines, mowers, generators, motorcycles and Can Am side by side. I'd like to use it in my Himalayan so I wanted to check with some oil experts here to see if this would be a good application for the Delvac. As I understand, a full synthetic oil can withstand much higher temperatures and shearing than conventional oils. With Delvac being a proven product over the years for OTR diesel trucks, and being a synthetic, I would think that it would likely outperform a 15W50 or 20W50 synthetic blend or conventional oil in an air cooled motorcycle. I have no problem buying those thicker oils, but since I already have lots of the Delvac 1 ESP on hand, I'd prefer to use that. I also like the idea of the Delvac being thinner so that it gets to the valve train faster to reduce cold start wear and tear. I live in West MI where riding temps are typically between 60 and 85F.