[DeTomaso] Steering rack adventures/ oil specs

[JDeRyke at aol.com]

In a message dated 8/4/08 6:11:11 PM, adin at frontier.net writes:


> What do we think of the new trend (ok, not so new) of specifying water thin 
> oil in transmissions?
> 
> Do we know more than the engineers?  If one were to use "better" (my term) 
> lubricant, will it void the warranty?
> 
Not a matter of knowing more; this was strictly a bean-counter move. In 1982, 
GM started adding ATF, a hydraulic oil with no load-carrying additives, to 4 
speed trannys. The zero-wt oil dropped the internal drag enough to raise GMs 
CAFE (corporate average fuel mileage) rating. And the few performance owners 
that fragged their trannys and differentials   were cheerfully warranty-replaced 
but didn't significantly affect The General's bottom line. I bought one of 
these with 12,000 lightly miles on it and 6 months later seized the tranny in 
2nd gear at an autocross. I drove across town with the gearstick in Neutral and 
on teardown, it took a torch and every bit of my 12-ton press to break the 
normally-rotating 2nd gear free of the mainshaft. 
I used to have phone numbers at some of the Detroit factories, so I called 
and asked what the idea was of running ATF in a std trans. The engineer that 
answered the phone at the Powertrain Division tried to tell me they're redone the 
internal clearances and metallurgy for ATF. As it turned out, the Z-28 trans 
was a Saginaw 4-speed; when I told him I'd mic-ed everything, found no 
differences so I repaired it with NOS gears from a 1966 Corvair Saginaw with 
"non-upgraded' gears and 90-wt gear lube, and   it ran just fine except cooler, there 
was no answer. The next time I tried calling (when the differential went out 
at 26,000 miles- 1 K out of warranty), the phone number had been changed.... At 
least three Nor-Cal Corvette owners also lost trannys and one diff until the 
news of the wrong lube got around.   
FWIW, I have now lost three (3.0) Chev posi differentials- 2 in brand new 
cars and one in the low mileage '82 Z-28. I am now convinced that GM cannot set 
up a posi differential; and the next new car I buy will NOT be a GM. 
As far as warranty goes, do you really want the thing fixed exactly like the 
one that broke? On the latest- Judy's '97 Z-28, I didn't even bother with the 
warranty. I took it to a performance shop to fix it right for $1000. The shop 
owner said they saw an awful lot of this stuff. FWIW- J DeRyke



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