i use it mainly because it still has the right amount of sinc that i need for my current car. which is a 67 plymouth with the slant 6. i used it in my 93 4cyl mustang with out any problems. uhaul uses it in all of its trucks and has for years as well.
I used 20-50 multigrade Mobil in mine after rebuild(1600 Hecho en Mexico motor). Used 10-40 too but in the summer it's insanely hot here(over 100 daily).
I change oil every 1500 km. Very dusty and I'm not sure about the gasoline quality here.
Roger
Mexican Bug
Puerto Vallarta
"The purpose of life is to enjoy it before it ends".