ZF4 HP22 - What trans fluid should it use?

[pundit]

Yes I'm going to buy myself a Bentley manual :D but in the meantime what's the recommended transmission fluid for use in a ZF4 HP22 - synthetic? Are the ZF's supposed to use the 'lifetime' fluid like the GM's in the later E34's?
My 535iA has only 105,000 miles on it so with luck I should still have some life left in the trans... ???? - Cheers :)

[gale]

The ZF4 HP22 does very well with synthetic ATF, be it Redline, Mobil 1, Amsoil, etc. This trans does not have "lifetime" fluid and requires routine fluid changes, every 15k-30k depending on driving conditions. The original spec for this trans when new was Dexron II which is no longer available. Dexron II has been replaced with Dexron III which is a Dexron II/synthetic blend. It is safe to add full synthetic ATF to your trans in any ratio. Approx. 3.5 quarts will come out when you drain it. You might get closer to 4 quarts out of it if you elevate the front and let it drain overnite. Measure how much ws drained & replace with the same amount of new fluid. These trannies respond well to partial drain & fills, approx. 50 miles apart. You should notice shift improvement after the 2nd 3.5-4 qt. partial drain & fill with synthetic. Continue with drain & fills at the same time as doing engine oil changes. Your trans should easily last beyond 200k if you do this, barring any prior abuse. After 2 or 3 drain & fills, drop the pan & change the filter. Clean the pan & magnets thoroughly. Some residue on the magnets & corners of the pan is normal.

Mine had routine dealer service up to 110k. I acquired it at 131k and started with synthetic ATF at 145k & was still running perfectly at 161k when I sold the auto & installed a manual.

[kngpen]

I am happy with royal purple ATF