ZR-1 Net Registry Forums - View Single Post - Fidanzza flywheel and transmission 10W60 oil?

Paul Workman · 05-19-2011

I had what is apparently a common failure with the ZF transmission - the reverse gear seizing to the idler shaft due to (as Bill Boudreau of ZFdoc.com put it) lack of lubrication. One minute I was cruising down the highway, and suddenly I feel a tug, like someone applying the brakes. In a matter of seconds the rear wheels lock up and skid to a halt!

I ended up buying a new transmission, and Bill opened up the oil galleries to better lube that reverse idler gear, and he recommended the Castrol TWS 10W-60 synthetic oil. (see excerpt from his web page)

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ZF Industries North America, that Engineering of ZF Industries in Germany determined that the BMW imported Castrol (RS superseded by TWS) 10W-60 oil was the recommended alternative to the (GM P/N 1052931) factory-fill oil for use in the ZF S6-40 transmission.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

I too had some rattle with my Fidanza, but Marc increased the idle speed by 100 rpm. That helped, but the biggest improvement came as result of replacing the injectors, due to 3 of my OEM injectors were going bad. The combination of the rpm, good injectors, and TWS 10W-60 oil, and I have no gear rattle at idle.

So, I guess my point is that manufacture recommends the Castrol TWS, (or the equivalent), and being a little paranoid (now) of oil-related (lack of oil) failure, I use the TWS 10W-60 synthetic and WATCH the level carefully!

FWIW,

P.

05-19-2011	#2
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Re: Fidanzza flywheel and transmission 10W60 oil? I had what is apparently a common failure with the ZF transmission - the reverse gear seizing to the idler shaft due to (as Bill Boudreau of ZFdoc.com put it) *lack of lubrication. One minute I was cruising down the highway, and suddenly I feel a tug, like someone applying the brakes. In a matter of seconds the rear wheels lock up and skid to a halt! I ended up buying a new transmission, and Bill opened up the oil galleries to better lube that reverse idler gear, and he recommended the Castrol TWS 10W-60 synthetic oil*. (see excerpt from his web page) (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. I too had some rattle with my Fidanza, but Marc increased the idle speed by 100 rpm. That helped, but the biggest improvement came as result of replacing the injectors, due to 3 of my OEM injectors were going bad. The combination of the rpm, good injectors, and TWS 10W-60 oil, and I have no gear rattle at idle. So, I guess my point is that manufacture recommends the Castrol TWS, (or the equivalent), and being a little paranoid (now) of oil-related (lack of oil) failure, I use the TWS 10W-60 synthetic and WATCH the level carefully! FWIW, P.