Transmission additive

Is there a good additive for a slipping transmission?

Not in my humble opinion.
That opinion might vary a microscopic bit, maybe, if I knew the type of car, mileage, if the fluid is low or darkened, how long the trans has been slipping, when or if the trans fluid was last changed, if it’s an older vehicle with an out of adjustment TV cable, or what station the radio is currently on.
You’ve provided no info at all on the car.

Don’t try one unless someone here has tried it first. Usually there aren’t any good random choices. If the transmission is already slipping, don’t even bother to change the fluid or it will get worse…

Holy water.

A good additive would be fresh transmission fluid. When was the last time you had it changed?

I’ve had some success with K&W TRANS-X. But don’t consider this as a permanent fix. It might get a few more miles out the transmission before it needs to be replaced.


1999 Taurus, 110K, oil level good,auto trans, slipping past 3-5k

NO! There are no additives that can fix a mechanical problem.

Agree, a slipping transmission should be fixed. A friend last month asked me the same question,in connection with a Mazda 626. I referred him to a reputable shop.