While not implying I'm any sort of an expert , I do know you gotta be "careful" with the GL5 gear lube stuff now on shelves. Before GL 5 rated gear lube, it was all GL4 which either doesn't have any or has much less sulphur than GL5. This sulphur in the GL5 stuff is not good for some trannies (like Chevy Muncie's for instance http://www.chevelles.com/forums/showthread.php?t=132305) or Nissan's SE-R's transaxles. It is not compatable with some parts like brass and/or bronze. I use the Spirax in the Alfa's gearbox because I haven't (yet) seen or heard otherwise that the current Spirax on the shelves is no good for it.
Originally Posted by Ish-Man
Wait a minute, you mean SpiraxHD isn't SpiraxHD?
Shell does offer a SpiraxLS, which I thought was Spirax with additional friction modifiers. I thought the SpiraxHD currently available, though GL5 rated, did not have friction modifiers, and was appropriate for Alfa transmissions and syncros, as well as differentials.
Take a look at the Shell spec sheet on SpiraxHD:
Loud pipes save lives.
1973 GTV - bought 3/06, intend to keep forever
1969 GTV, #AR1530021 - sold 10/72, guess didn't intend to keep forever
Current project: '69 Corvette bought in '73, DD '73 - '80, in storage 1989-2002, now apart