Lazy man's tranny fluid maintenance

[motordavid]

with exc. opin posts by JCL & Weasel.

My fave bro-in-law owns/runs an AAmco Trans joint in north
Jersey and he suggests half his trans work is on cars that have
recently had the auto trans fluid "changed/flushed", etc.

The age of some of the heaps he gets obviously has some
correlation, but a "feel good" auto trans fluid change is not
rec'd by him.
Fwiw, he does a few assorted BMWs per month, and says if
he would not touch the fluid in those until the trans croaks.
GL,mD

[X5 Meister]

So what would be your cutoff (if any) for a fluid change on a car that you planned on keeping? i.e. let's say you got a brand new X5, would you change it and at what mileage?

And in case you didn't see it.. check out post # 62 on this link:

http://www.xoutpost.com/bmw-sav-foru...tml#post628564

[JCL]

Originally Posted by X5 Meister

And in case you didn't see if.. check out post # 62 on this link:

http://www.xoutpost.com/bmw-sav-foru...tml#post628564

I don't know the composition of that ZF additive in the link, but I would bet that it is a friction modifier, designed to solve problems relating to one of the clutches on some models of ZF transmissions. Same problem existed years ago with Ford transmissions, and the additive was designed to help the transmission deal with a hanging clutch in the event that the customer reported problems. Putting the additive in when it wasn't required was worse than using the wrong fluid.

Or, it could be a miracle cure designed to double transmission life. But I doubt it.

[JCL]

Originally Posted by X5 Meister

So what would be your cutoff (if any) for a fluid change on a car that you planned on keeping? i.e. let's say you got a brand new X5, would you change it and at what mileage?

I wouldn't change it unless I had a shifting problem, and then I would consider it just postponing the inevitable.

I bought a brand new 2003 X5 3.0 Steptronic, towed occasionally with it, and never changed the transmission fluid (not lazy, just could see no reason to do it, ever). Reasons as listed throughout this thread. Sold the vehicle at 73,000 km. Drove great, but then it was still very young.

Bought 2 x Explorer, 2 x Expedition, 1 x Taurus, all new with automatics, over the years (plus many more cars with manual transmissions). Explorers and Expeditions were driven in extreme conditions, with significant off road mileage. 66 Mustang was purchased bagged, fully restored and transmission rebuilt as part of the restoration, including a shift kit. Never changed the transmission fluid in any of the above vehicles. Never had a transmission failure, in 33 years of owing various vehicles. Lots of preventative maintenance, just no transmission fluid changes.

[JIMROD]

my 2 cents ...leaving a perfectly good working trans enclosed eliminates 2 other factors in trans failures(also applies to all things lubricated) the dealer concerned with profits using cheap fluid(or broadspectrum) instead of the high tech correct stuff(yes unfortunately there are too many choices) and the mechanic getting contamination in the once sealed unit. I too would like proof that frequent changes work. Really I am still on the fence, what failed first the lube or the part quality? was it the chicken or the egg?

[Weasel]

Originally Posted by JIMROD

my 2 cents ...leaving a perfectly good working trans enclosed eliminates 2 other factors in trans failures(also applies to all things lubricated) the dealer concerned with profits using cheap fluid(or broadspectrum) instead of the high tech correct stuff(yes unfortunately there are too many choices) and the mechanic getting contamination in the once sealed unit. I too would like proof that frequent changes work. Really I am still on the fence, what failed first the lube or the part quality? was it the chicken or the egg?

Frequent changes would not stop clutch pack breakdown, even if you had a constant supply of brand new high tech expensive fluid the clutch packs would still wear down over time.... that is just the physics of how it works. If the transmission failures were due to fluid lubricity failure it would be bearings/actual gears and metal parts that failed, but the friction material on the clutches will inevitably wear regardless.

[JIMROD]

GOOD POINT...

[JIMROD]

GOOD POINT, so you have seen clutch packs as the most common failure mode?

[c4racer]

Originally Posted by Weasel

JCL hit it pretty good And in my non BMW experience from previous shops was that the clutch material in the fluid added some viscosity and changed the friction profile of the fluid, so when people changed all the fluid of an older, higher mileage car the transmission would inevitably start slipping. (I'm sure not being able to reset the trans adaptations with the fluid change didn't help)

I've personally seen more transmission failures on transmissions that have been serviced than one ones left alone. And since I got the vehicle with over 80k miles, I couldn't see any good coming of a fluid change. Now with over 90k miles it still drives perfectly and I'm waiting to see how long it will go before I have to go all swissfrank on her ass.

So based on all this I have decided to stick with the original fluid in my 4.6is that is about to go past 100K miles.


But what about my wife's car - Mazda Protege. I replaced all the fluid at 60K miles with Mobil 1. Should I just leave that until the trans dies? Or replace every 60K?

[Weasel]

For the protege, I can't tell you. They use a different quality fluid that may break down over so many miles. I'd just follow the fluid change intervals put out by Mazda.