Join Date: Oct 2001
Location: Momence, IL 60954
It's all on the link to the oil article on my website. It appears that m1 15w50 hasn't changed much from what was sold over 10 years ago, in my testing. I also tested some oil school kendall gt-1 from the 70s, and the levels of Zn and P are pretty much the same as what they put in m1 0w40 and 15w50 (as well as m1 20w50 vtwin m/c).
And on my type 4, I was running single hd springs roughly the same as stock. The factory rocker arms have little galleys in them that are force fed oil through the lifters and pushrods to the rocker arms, that oil the valve stem, face, spring, and guide. At high rpms, there is enough oil in the head to lubricate with the pauters, but at low rpms I've heard of people who could hear the valve train squeek from lack of lubrication.
Charles Navarro, LN Engineering
Aircooled Precision Performance
'99 Boxster powered by Flat 6 Innovations; '10 Cayman S (DFI testbed)
Last edited by cnavarro; 01-22-2007 at 08:52 AM..