engine and gearbox additives - yes or no?

[oswestryalex]

The problems with the auto transmission I have heard of make me think it a wise move to get the trans fluid and filter changed as soon as I get the car, as well as an oil filter and oil change - that I always perform on a new/old car. Question is - I have in the past used friction reducing additives in the engine. There are similar products for the transmission available. Would they make a difference to how well the trans will run and its longevity? Some additives claim improved mpg too... that I am a bit skeptical about. Cheers, Alex.

[JOE-DOT-COM]

Hi

Some additive are ok in basic stuff like engine's

but using additives in auto boxes are really a no no,

most additive's are friction reducers and you dont want that in a gearbox, it can cause the friction plates to slip and also most auto gearboxes have a lockup clutch in the torque convertor, you don't want this to slip either

additives are also no good in gearboxes with LSD's in and

I recommend just using descent oils, I use  Castrol edge proffesional in mine and Genuine ZF oil in the gear box, Castrol Again in the diff

cheers

Joe

[oswestryalex]

I do reckon that with an older car purchase a change of oils is probably a good idea unless they have been definitely done recently. I did get a Volvo secondhand with brand new fully synthetic oil in there and new filter - the seller had only just done those when his replacement car arrived... so I had about 6 months of driving before I decided to change on that occasion. With the auto boxes on the S Types having such a bad reputation, I was looking to find ways to avoid problems down the line - but additives may well be a step too far; friction reduction in a gear box may not be the best idea...  - for which cheers! One assumes all friction is 'bad' but actually....