I find a 15W40 oil works well in my '85/22RE. Have also used a 20W50, but the 15W40 seems to work as well. Plus I use the same stuff in my VW diesel.

My engine is not so much noisy as I find with a thinner oil I find the hot idle oil pressure falls down to the bottom of the factory gauge if I run anything lighter than 40 in it, like a 10W30.