THE stuff to use is GM Synchromesh Transmission Fluid, part number
1#12345349. It's a synthetic, lightweight gear oil used in the 5 speeds
in the Buick Grand Nationals. Get it at your Buick dealer (about $7
per quart and you'll need about 2 quarts). Several members of the TR8
Car club have been using this stuff (some for 3 years or more) with
splendid results.
Haven't heard of anyone who has tried the Castrol. RedLine MTL does NOT
work; they're formulating a special lightweight version of MTL but it's
still in the testing stage. Amssoil (sp?) may have something too but I
haven't heard of any experiences with that product line.
As Bill pointed out, straight 75W (what the gearbox was originally designed
to run with) is too thick for the little gear pump inside the box, especially
when it's cold. ATF was just a kludge by JRT; they're really weren't any
better alternatives at the time. The gearbox was NOT built for ATF.
80W-90 will NOT work! I ruined my gearbox by topping up with 80W-90.
--> gear pump failed, gearbox didn't get lubed properly, 2nd
goes, 3rd starts to go, I get the car home pronto and had to rebuild
my box MUCH sooner than I'd expected. :-(
Hope this helps,
jim
|