way back then -- Steen C oil and alky
Now I run in my ZDZengines - 35% Redline Racing Oil -and gasoline
The business of trying to measure after the fact -to me , is ludicrous.
I run em and listen to em - if you have trained your ear - you can tell when the engine peaks and when it is too warm
also you can tell rpm - as rpm is a frequency thing .
you can't hit exact rpm -but close .
When I played music - ( I was trained on clarinet fom age 7) I learned to hear very, very small changes in pitch .
Ask any classically trained musican -