Amsoil Briggs racing oil .
You'll find lots of opinions .
14-16 oz .
Nothing beats fresh clean oil , changed often .
The 4t i believe has a rust prevention additive.
I run plain Pennzoil or Rotella 30WT in our clones and Predators and engines all look great inside after 10-12-15 races. Change it often and keep the air filter clean, you don't need $15/qt oil for these things...
We ran zero wieght red line in one of ours . Can't say its what got the wins , it did not hurt anything . Budget racing it may not be the choice . It for sure is cheap hp if theres any gain .