Hello All,

My "GEARBOX FAULT" warning has not recurred, even once, since its appearance on Wednesday, June 19th. The fact that the car had not stored any power train DTCs makes me a bit more sanguine that this is not a catastrophic failure in the making, but some transient issue.

However, to my knowledge the transmission fluid in this car has never been changed. At just under 150K miles, I really don't trust "sealed for life" transmissions to have anticipated a life this long in years or miles.

In my brief review of JTIS this job seems not to be particularly difficult, per se, but terribly tedious and probably messy since there is no drain plug (or else I missed that during my quick review).

Has anyone every done this job in their driveway? I've got a set of ramps and also jack stands, so I can get the car in the air more than far enough to have access to the transmission pan and the 21 bolts that hold it in place.

A replacement gasket would definitely be needed as well as a replacement filter (unless the filter is a simple screen). Are there any other things (besides the correct ATF) that one must have either in tools or supplies? Would I have to be nuts to even consider trying this at home?

Submitted by vogelbp@gmail.com on Mon, 07/01/2013 - 23:50

Steven,

Your advice to me has been consistently useful, and this is no exception.

I would like to know your opinion as to what might have caused a transient "GEARBOX FAULT" alert without any stored power train codes? I live in mortal terror that I could be driving along the highway and, *WHAM* the transmission just self-destructs.

Unfortunately in these cars the lack of a dipstick or any easily owner-checkable metrics for the transmission makes these mysterious disappearing faults all the more unnerving.

Submitted by stevejag@sbcgl… on Mon, 07/01/2013 - 16:34

I'll pass along something I've lived by for a number of years.......granted, you'll find folks that will tell you I'm full of crap. But this idea has served me well since these cars were new.

In a discussion with a ZF tech guy, the idea of 5HP24 and 6HP26 fluid changes or recommendations came up; and what he had to say made sense.

We call them 'fill for life' because of two things. First, fluid technology has come a long way, these are either semi-synthetic [5HP] or full synthetic [6HP], the fluid DOES NOT break down or oxidize like petroleum fluids of the past. Second, these are 'adaptive' transmissions, meaning they adapt or takeup for wear of internal parts and friction discs, etc. We all know the friction discs in there wear over time. That friction material doesn't disappear into oblivion, it becomes suspended in the fluid and keeps going 'round and 'round. That means that friction material still has a roll to play in those clutch packs, and the TCM adapts accordingly. So he asks me, "Ever heard a guy complain he did all the right things, including change his trans fluid, and still his trans 'failed'?? It's likely because he threw out all that friction material [the part in the fluid] right out with the bathwater." Consequently, the clutch packs no longer worked the way they did before, and the trans slipped or shifted badly.

Since then, I have never recommended 'routine' trans fluid changes. I leave the fluid alone, and don't worry with it unless there is a failure or a leak. I don't feel his advice has ever failed me.

But, like I said, plenty of folks will disagree with me.

Just my two cents.........