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Old March 18th, 2006, 03:23   #22
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Join Date: Jan 2004
Location: NYC area, NY

I meant it would be a straight 75, a straight 90 would test at 13.5+ at 100, not 6.3. So either it is a XXw-75, or a straight 75. Isn't the higher number the visc at 100C??? Didn't they test the G52 at a 75 weight viscosity at 100C?

So then, if it is a straight 75 (not even a 90) it would be thick like molasses at 0c, or so. Our trannies probably don't even hit 100C on normal driving conditions, so that may be why they use a 6-7 cst fluid at 100C. But then, a straight viscosity oil would be less prone to shearing, so maybe its a cheap way to make VW be able to run dino oil.

One thing that perplexes me, is the stories of how Specialty Formulations MTL-R does so well in our O2J trannies. Its a 75w90, with 14.5 or so at 100C. Maybe they run a huge VI, like the pennzoil syncromesh (which is at 190 or so VI).

Anyhow, the crazy VW price makes me go ugh about G52 and G50. I'll stick to Pennzoil Syncromesh (w/ more often changes), or Specialty Formulations MTL-R or MTL-P.

Originally Posted by SUNRG
first - i just threw that out there that this may be a straight 75, it could be a multigrade - i don't know. however...

the above is not what i understand would be the case. multi-grade oils start with a light base oil and add viscosity improving (VI) additives so the oil will not thin too greatly when hot. a multi-grade 75 with VI additives, like a 75w-90, would test as a 90 at 100c (13.5+ cSt). a straight 75, without VI additives, would test as a 75 at 100c (approximately 4.3 to 7.2 cSt).

if G52 were a straight 90, then robnitro's theory that "it would thicken up a lot with lower temps and be notchy like david_594 experiences" could be accurate.

but, knowing what we know, i doubt david's cold tranny notchiness is a result of G52's viscosity. it could be that G52 is not the best choice for use in transmissions where G50 is specified or it could be, as tonglsi suggested, that possibly david's shift cables could use calibration.

DD - the G52 that is synthetic is NOT specified for use in our tranny's, it's a 2004+ 02M fluid. part number G052171A2.
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