aDigitalPhantom

This is not about what oil to use that has been beat past death many times over.

I noticed my PDF owner's manual says
But according to ZF
The question is...
How often do you change your transmission fluid?

steve1657

Was just looking for same, found this old post.
Lots of specs on the oil, but also point 8 about how often to change.

I hope this helps


Re: Castrol Lubricant for ZF6 Transmission (LT4BUD)
http://www.fzdoc.com BMW part number 07510009420 it's engine oil for the M5, and it's not cheap either. 2 bottles should cover you for a complete fill.


"(Q.) I just bought, at the local BMW dealership, 3 liters of the Castrol TWS 10W60 oil. I was surprised to see that it is motor oil. Not being a lubrication engineer myself, who did the investigation and determination that this product is compatible with and good for our ZF transmissions? Jim – Grand Sport Registry

(A.) Jim, the C4 Corvette ZF S6-40 6-speed transmission uses engine oil for lubrication. I was told by Jeff Henning, Warranty Administrator of ZF Industries North America, that Engineering of ZF Industries in Germany determined that the BMW imported Castrol (RS superceded by TWS) 10W-60 oil was the recommended alternative to the (GM P/N 1052931) factory-fill oil for use in the ZF S6-40 transmission. In effort to verify ZF Industries alternative lubricant recommendation, we ran our own test series on the BMW imported Castrol TWS 10W-60 oil. Independent testing of the transmission oil samples was sub-contracted out to CTC Analytical Services. The test series went as follows:
<1> Spectrographic analysis indicated that it is has full synthetic composition.
<2> After 2 hours of operation, approximately 100 miles, oil sample analysis tests indicated that the viscosity rating was reduced from 60 down to a 43 level. No need to worry, this is a normal occurrence for this heavier type of oil. I attribute this to microscopic-level lubricant-strand trimming through operational loading where all of the oil contents has been passed through gear pressure-loading regions at least a few times.
<3> At 200 miles, the viscosity level stabilized at a 42 level viscosity since the 100 mile oil analysis test results.
<4> At 5000 miles, the oil analysis test results indicated a 40 level viscosity.
The test-transmission was completely disassembled and checked for wear. There were no signs of carbon film like experienced with the factory-fill oil. The phosphor-bronze lined synchronizers had no glazing and experienced an average mass loss of approximately 4% based on reserve-wear-range mass equivalency between 0.062"(new) and 0.048"(spent)
gap wear/mass measurements.
<5> At 10,000 miles, the oil analysis test results indicated a 39 level viscosity.
<6> At 12,500 miles, the oil analysis test results indicated a 37 level viscosity.
<7> At 15,000 miles, the oil analysis test results indicated a 34 level viscosity.
The test-transmission was again completely disassembled and checked for wear. There were no signs of carbon film like experienced with the factory-fill 30 oil. The phosphor-bronze lined synchronizers had no glazing and experienced an average mass loss of approximately 17% based on reserve-wear-range mass equivalency between 0.062"(new) and 0.048"(spent) gap wear/mass measurements.
<8> At 15,000 miles the oil had enough phosphor-bronze particles suspended
in it that deposits began building up inside of the synchronizer sliding
sleeves from the normal centrifuge-like rotational occurrence.
In Conclusion, until someone invents a copper magnet, we recommend that the ZF S6-40 6-speed transmission oil be changed at 10,000 - 12,000 mile intervals so as to minimize the amount of deposits of the suspended spent synchronizer material from collecting in critical component contact surface areas. "

TorchTarga94

^10-12k is a good idea. Personally I go 15k (mainly highway) on Amsoil Syncromesh. Might not be a bad idea to cut that number in half if you track the car regularly. Just a peace of mind thing really. I am pretty sure my ZF still had the factory fill oil in it when I drained it at 92k miles. Mine still shifts like butter. The transmission will tell you when it wants a fluid change usually.

DGXR

I have done some research on this and I will be changing mine every 2 years, which works out to about 12,000 miles (60% highway 40% city). I put it up on jack stands every year anyway, to bleed the brake and clutch hydraulics and check the diff/trans fluids, no problem to drain & fill the transmission while it's up.

aDigitalPhantom

I have been thinking about adding a filter, and yes I know it would require a pump to move the fluid. Would the fill and drain plugs work for this?

WVZR-1

The drain plug I believe is to low to allow this. The drain plug is nearly the lowest most point of the car. Many drain plugs have been demolished by speed bumps and the like.

aDigitalPhantom

I'll have to look, but IIRC the bottom of the bellhousing lower on my car.

Update
Still need to look. I did not feel like looking under the car with it snowing.

Update 2
I was right, but its the same level as the drain plug.