ZF-6 oil

[Mystic ZR-1]

This has probably been covered many times somewhere on the site, but:
I'm rounding up the stuff I'll need to recommision the Z for the coming season. The FSM, pgs 0B-12 & 13, calls for SAE 5W-30 (GM PN 1052931 or equivalent) 4.4pt/2.1L, for the ZF 6 speed.
Castrol 10W-60 seems to be the Forum's choice.
What's best?
Thanks!

[FU]

Castrol 10W-60

[GOLDCYLON]

The ZFDOC reccomends the BMW oil which is the same oil as the castrol

www.zfdoc.com

Q&A off the above site

(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ZF Industries North America, that Engineering of ZF Industries in Germany determined that the BMW imported Castrol (RS superseded by TWS) 10W-60 oil was the recommended alternative to the (GM P/N 1052931) factory-fill oil for use in the ZF S6-40 transmission.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

[vilant]

I used the Castrol TWS 10W-60, and everything is running like a well oiled machine. Ordered it online from, think it was a BMW dealer, Turner Motor sports. Anyway, I could dig up the info if you want it.

[scottfab]

Originally Posted by Mystic ZR-1

This has probably been covered many times somewhere on the site, but:
I'm rounding up the stuff I'll need to recommision the Z for the coming season. The FSM, pgs 0B-12 & 13, calls for SAE 5W-30 (GM PN 1052931 or equivalent) 4.4pt/2.1L, for the ZF 6 speed.
Castrol 10W-60 seems to be the Forum's choice.
What's best?
Thanks!

I still use the original GM stuff.

[mike100]

I prefer the shift quality using Amsoil synchromesh. It is thinner if that bothers you, but I think it may be closer to the original gear oil weight.

[secondchance]

http://www.zf.com/na/content/en/nort...faq_pc_us.html

If you scrol down about half way it says:

What type of oil do I need to use in my ZF S6-40 Corvette transmission?ZF only recommends the following lubricant for S6-40 transmissions. The GM oil (available from GM with part number 1052931) and the Castrol Synthetic Formula RS 10W60 (available from BMW with part number 0751009420).What type of oil do I need to use in my ZF S6-40 Corvette transmission?ZF only recommends the following lubricant for S6-40 transmissions. The GM oil (available from GM with part number 1052931) and the Castrol Synthetic Formula RS 10W60 (available from BMW with part number 0751009420)."ZF only recommends the following lubricant for S6-40 transmissions. The GM oil (available from GM with part number 1052931) and the Castrol Synthetic Formula RS 10W60 (available from BMW with part number 0751009420)."

[MRC1994]

What is the capacity? How many quarts do I need?
Thanks,
Greg

[mike100]

Originally Posted by MRC1994

What is the capacity? How many quarts do I need?
Thanks,
Greg

2.2 qts, but you need 3 bottles. Of course a little spills so you end up with 2/rds of a qt left over to use as a topper.

[MRC1994]

Originally Posted by mike100

2.2 qts, but you need 3 bottles. Of course a little spills so you end up with 2/rds of a qt left over to use as a topper.

Thanks,
Greg