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TR2/3/3A Gear oils for TR3

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prb51

prb51

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Gents, I am using a GL4 90 weight for my gearbox in deference to the yellow metal issue. Should a GL5 be used in the dif?
 
MT90 says it is GL-4 though I do not know if it has stuff in it that is bad for copper alloys.

75W90 NS says GL5 and that it contains "improved copper corrosion protection which prolongs the life of synchronizers". This is the flavor that Moss sells.

MT90: https://www.redlineoil.com/products_gearlubricants.asp?pvID=74&prodID=57&subcatID=18

75W90 NS: https://www.redlineoil.com/products_gearlubricants.asp?pvID=109&prodID=57&subcatID=18

Yes, my understanding is that there is no brass or bronze in the diff.
 
GL4 is ok for yellow metals and GL5 is not. The chem compound that allows for the GL5 rating degrades yellow metals. Thanks for the info, I've been running GL4 in both but the redline should be better protection for the dif.
 
You can call me nuts but I swear by STP mixed with 90 for the diff. I had a bad bearing in a diff that made noise, too broke from college, I changed the sick old grease and mixed in 40% STP. It was quieter and in fact ran well for the next 17 years!!
MD(mad dog)
 
I don't know how corrosion prone they would be, but the thrust washers behind the sun and planet gears are some variety of bronze.
 
Trtel, Was unaware of that. I won't use a GL5 in that case. Napa sells GL4 by the gallon and that's what I've been using. Not going to take a chance on a 50 year old rear end (mine or the cars).
 
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