Snake oil success!

[alberniken]

Hello all, especially those with tranny issues (The automotive kind only please)

TL;DR - magic witches potion fixes transmission

Essay version:

A few months back I bought a second x5, 2003 4.4.

Overall nice condition, and has quite a bit more "git up n scoot" than my 2001 3.0.

One drawback was torque converter lockup being intermittent, accompanied by a slight shudder. At steady cruise around 2000rpm, it would switch lock/unlock about every two seconds. Also experienced loose or soft gear changes, like the transmission was uncertain it wanted to keep the gear or up-shift.

Much research on this forum, other BMW forums and sites that cover ZF transmissions got me worried that the only option was new TC and rebuilt transmission. I talked directly with a transmission re-builder and he noted that there was a common issue with seal leakage that would bleed pressure for TC clutch mechanism, and cause 'loose' gear shifts. Worst case was the a seal (or more than one) might have gotten torn or eroded.

A general search into transmission problems, especially high mileage units with indifferent maintenance, led me to try a less expensive chemical solution first.

The seller had fortunately included several litres of ZF fluid with the car, so I decided to at least try a solution often derided as "snake oil". In addition to the ZF fluid, I ordered AT-205 Re-Seal and Lubegard 19610 Instant Shudder Fixx

Got the car up on stands and drained trans fluid - WOW was it black! Especially a concern as the ZF fluid was nearly clear. Drain & fill just what was in pan, drop it down and go for drive. I just puttered around to ensure the new fluid could get to all the nooks and crannies.

Up on stands again for drain & fill; WOW again, better but still dark. Another scenic drive around the neighborhood.

Third time around, drain & refill with the two chemicals above, plus top up with ZF fluid. Got for ride around town. Shifts are a -little- better and there is a hope. On longer steady sections, still had the lock/un-lock TC problem. I did think that maybe the lubeguard reseal would take some time.

Sure enough after about 500km I have now found the TC lock/un-lock issue has disappeared! I can cruise at a steady 2000rpm and not see a glitch at all. In addition, the gear changes have definitely tightened up a whole lot.

Now I know that some folks will say it was the fresh ZF fluid that made the improvements, but I have experienced a number of transmission issues on quite a few vehicle (since I tend to buy a lot of end-of-life beaters) and know from my own experience that other than low fluid levels, I have not ever seen fresh fluid fix problems such as this.