Hi guys,
I keep getting different opinions on when, or when not to change transmission fluid. Is there any routine maintenance that applies to all cars, specifically BMW, Porsche (German...)?

Also, I've been told that if you haven't changed tranny fluid in a long time and the gears are not shifting smooth, it is better to leave the fluid in the transmission since newly replaced fluid is "smoother"and will cuase gears to shift even less smoother! Do you guys agree? I thought no matter what is the case with the transmission, changing the fluid is always a good thing? When purchasing a used car, wouldn't changing the transmission fluid be part of the usual "fist things to do" (along with oil, sparks, timing belt etc...?)

Any info would be appreciated!
Thanks,
Mike

 

I think Porsche says 2 years, 24,000 miles. Redline says you can go "longer" with their synthetic products.

If you have old gear oil, definately change it! I know it helped in my car. I use Redline MTL (GL-4 rated). A lot of people on this list choose to use the GL-5 rated 75w90 or 75w90ns. I just get nervious thinking of my synchros sitting in the GL-5.

 

I agree with Tabor !Thats exactly what I did ,very noticable ,smooter shifting!

 

[quote]Originally posted by Mike 944:
<strong>Hi guys,
I keep getting different opinions on when, or when not to change transmission fluid. Is there any routine maintenance that applies to all cars, specifically BMW, Porsche (German...)?</strong><hr></blockquote>

Porsche suggests 60k miles for manual transaxle, 30k miles for automatic. This figure is common for most cars, regardless of origin.

[quote]<strong>Also, I've been told that if you haven't changed tranny fluid in a long time and the gears are not shifting smooth, it is better to leave the fluid in the transmission since newly replaced fluid is "smoother"and will cuase gears to shift even less smoother! Do you guys agree?</strong><hr></blockquote>

No, old fluid is old fluid - it has been broken down and mixed with contaminent (water, etc) - the reason to change is for renewed lubrication to prevent excessive wear. I'll generalize that anyone suffering from decreased performance after a fluid change either did it wrong, or used questionable fluid. There are volumes of information to be regurgitated on this, but suffice to say that changing the fluid - even more often than recommended - is_not bad for the car.

[quote]<strong>I thought no matter what is the case with the transmission, changing the fluid is always a good thing? When purchasing a used car, wouldn't changing the transmission fluid be part of the usual "fist things to do" (along with oil, sparks, timing belt etc...?)</strong><hr></blockquote>

Yes, and yes - change the fluid.

Good Luck!

 

[quote]Originally posted by Tabor Kelly:
<strong>I just get nervious thinking of my synchros sitting in the GL-5.</strong><hr></blockquote>Since GL-5 is recommended by the factory I'd be more nervous about my Ring & Pinion sitting in GL-4

 

And when you change it, remember this tip, originally (?) posted by Hans... be sure the _fill_ plug will come out before you take the drain plug out!!!!

Jim, "How embarassing!"

 

I have been using GL5 in my 87 951 since new.

No problems with synchros.