I found a few oils that are to spec:
the pennzoil syncromesh vs the pentosin MTF2 vs the redline MTL90 vs Castrol SMX-S
the correct kinematic viscosity of a 85 weight oil is somewhere between 7 and 14
SAE service level defines targets for a 75W gear oil to be= 4.1@ 100F and 7.0 based on that and the fact that folks using MT90 and folks using syncromesh by pennzoil are reporting better than MTL results
there is a rumor that the GM syncromesh IS pentosin, but I dunno
this led me to believe the MTL90 some guys on this forum may be my second choice so I did a little experiment that cost me $60
I dont put pennzoil in any of my cars
here is a list of their salient characteristics
penn synch * pentomtl 7580 * mtl90 7590 * smx-s
KV @100 * 9.08 * 7.7 * 15.6 * 11.9
KV @ 40 * 41.6 * 38.3 * 90 * 64.4
VI * 208 * 177 * 185 * 183
I dunno the weight of the syncromesh, and the smx is a 75w85
I had hoped better for the smx and the redline but they too are thick when cold
FAIL
SAE service level defines target KV for 75W gear oil to be= 4.1@ 100F and 7.0 based on that and the fact that folks using MT90 and folks using syncromesh by pennzoil are reporting better MTL results
see
http://www.finalube.com/reference_ma...Categories.htm
Pentosin is the lightest of oils, of the four above
I use their line up of oils in Porsche audi and BMW products in my garage
Its great to put something fresh in there, even better to know why it worked better, and less of a dice roll if you really know whats different about them.
I also considered
http://www.redlineoil.com/product.aspx?pid=140&pcid=7
its thick but not as thick as the MT-90, this one is specifically to address the cold synchro symptoms
BUT its a bit thick ish, and performs alot like the MT-90, but it MAY be an improvement