what are mechanics favorite additive to add to transmission oil?
Lucas is a good transmission additive that will also stop small leaks and promote better shift quality. of automatic transmissions
GOOD quality transmission fluid. If the additives were actually useful, they would be included in the formula for the original fluid.
Legitimate mechanics do not add anything to any fluids. If they actually helped on a long term basis they would already be blended into the fluids from the start. and a lot of the additives you can buy are redundant because they ARE blended in to begin with. Just don't put extra fluids in there because you will see no long term gains in performance.
