Since I run strictly 91 auto fuel in my 85hp, I should not have to worry about lead.
Zenairdave: what oil specifically are you running? I really find it hard to justify $120+ for 12 pk av oil up here. I'm real tempted to try diesel oil like Rotela thinking it may lend itself better to flat tappet type engines as opposed to roller rockers & modern auto oil.
Thought?
As a precursor, Remember----your results may vary.
The purpose of my experiment was not about saving money over the price of oil, it was about causing less harm to a cold engine with thick oil that will not circulate at cold temperatures. When it does start to circulate, it is likely bypassing the screen/oil filter until warmed up significantly. These are not desirable issues.
Other things I considered that were likely happening with cold thick oil.
Hyd. lifters not able to fill/adjust, oil not able to pass bearings making hot spots, oil not returning to pan, rings unable to scrap the cylinder properly nor get the gel out of the rings.
Potential risks with car oil include, not being able to handle lead, detergents that clean 50 years of sludge from internals and plug the screen, some secret ingredient that eats 75 yr old metal or seals. Maybe its not as slippery as Aviation oils??
When aero shell comes out with 5W30, I will gladly buy it at whatever price. Until then, the Castrol GTX synthetic blend for high mileage engines is what seems to be working. I was warned by someone to make sure it is rated with SL from API.
I never checked what that was because on the back it has stamped, meets SN,SM,SL,SJ. Whatever that rating is, it has it.
In the end, it's your engine, your money, your choice. Do what you want at your own risk.