[T2] link to Amsoil ASTM-D130 tests of gear oils safe for yellow metal synchros

[MUTS]

http://xlforum.net/vbportal/forums/showthread.php?t=1533539

Add to list: NAPA 80-90 GL3-4 oil, part #75-210
Sta-lube 85-90 Gl4 gear oil part # SL24239


I have an 091 trans in a 75 bus that was likely changed to a valvoline 
gl5 gear oil only a few thousand miles ago, but has sat when the was 
losing power (due to slipping clutch, changed a year ago, but then was 
leaking oil, then changed trans shaft and crank seals last month and on 
warmup (no axles attached yet) the engine oil leak is gone, but oil was 
seen to leak  gear oil from above nosecone- lost over a cup- stopped 
engine, cleaned it up, ran it again to see start of leak and no more 
leak!   Oil filler plug showed level was below fill hole. Next day did 
same- warmup, foamy oil came out over nosecone, likely from vent hole? 
Stopping engine, cleaning it and running again- no more leak! Now pulled 
fill plug, level is at least an inch below hole, and finger came out 
with foamy oil on it.  Drained all the oil, looks clean, magnet showed 
one tiny sliver.  Could it be water in this fairly new oil? Based on 
local sources, will use the NAPA $5 a qt gl3-4 oil.

    What I do not understand is the dual nature of my 091 trans- has a 
hypoid Ring & Pinion, but yellow metal in the synchros?

These synchros  will be damaged by the 2x level of sulfur found in Gl-5 
vs GL-4 gear oil made to protect modern manual hypoid gearboxes?  This 
level will prematurely eat the synchros and not let them grab.

The amsoil test lists GL5 brands that pass the test as safe for yellow 
metal.