The article is impressive, but, it seems to be relevent to watercooled engines more so than aircooled. I would be running #50 racing oil if it was still available here in Honolulu at my parts distributor. But since it's not available I run straight #40 Pennzoil in my 73 type 1 with a 1956cc engine. I change my oil and filter every month or 500 to no more than 700 miles on the clock.
I built the engine from the inside out in 2007 and drive it daily without any,
let me say again, without any, problems at all. Regular maintenance is performed every 3500 to 4000 miles to maintain peak performance. So where am I going wrong in using the #40 weight oil? If I'm doing anything wrong with my own machine, please enlighten me to the proper and recommended methods and proceedures.