[T3] milage spec to change Diff oil with auto trans?

[Jim Adney]

On 24 Feb 2016 at 13:49, William J wrote:

> I always looked in the Bentley and it only states replacing the diff
> fluid on two model years think 68 &9 . On later modles it only states
> replacing it if it's contaminated . 

I had no idea that this was different for '68-9. It's possible that 
improvements in gear oil made this possible, but it's also possible 
that VW's experience with this system was new enough that they were 
being cautious. I should also note that there are a few significant 
differences between those 2 generations of ATs, but I'm not sure that 
any of them would make any difference in the maintenance schedule.

I just looked at a 1970 owner's manual, the one from the glove 
compartment. It says the AT final drive oil should be checked every 
6000 mi and topped up if it's low. My practice has always been to 
change that oil any time I buy a new Squareback. It just seems 
prudent after all this time and miles. It also gives you a chance to 
look at the magnetic drain plug and see what it's captured.

Someone once mentioned to me that a lot of Type 3 AT gearboxes die 
because they sometimes run dry and no one notices. Checking every 
6000 miles would avoid this. There's the tendency to check the ATF 
dipstick and assume you're done. It's unfortunate that the final 
drive oil, like the MT gearbox oil, is much harder to check. If they 
run dry, it's likely because one of the output shaft seals failed, so 
that's worth keeping an eye on.

I have 3 Type 3 ATs, and they've all been fine so far. According to 
Russ, they were always quite reliable.


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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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