GM 88862472, transaxle fluid for F35/MU3 5-speed

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Sep 12, 2002
Has anyone found a synthetic fluid suitable for use in the GM/Saab F35/MU3 5-speed manual transmission? These are used in the Chevy HHR / Cobalt SS and the Saab 9-3. I heard it is a 75W-85 GL-4 synthetic, but GM wants $20 a quart and it seems too thin when warmed up.
Nissan, Kia, Hyundai.... have 75w85 GL4 for about $10. Or, you could thin Redline MT90 with 25% MTL, or Amsoil MTG with MTF to make your own full synthetic 75w85 GL4. The 85wt is all but ignored by US blenders/resellers for now.
I am not sure if the F35 needs an ATF-like fluid or if a gear oil could be used. I recall this being an issue in my TR-3650 because a gear oil could potentially corrode the blocking plate or isn't compatible with the paper synchronizers. Is the MT-90 suitable for gearboxes that need an ATF? I wouldn't mind running a straight 75W-90, the higher viscosity should help protect it at higher temperatures/loads.
Its not an ATF. Its a 75w85 gear oil. MT90 is a 75w90 GL4 gear oil. Is 88862472 a GL4 or GL5 fluid? A VOA or UOA of this fluid will give you some more answers.
Is that the Getrag trans? My info says ATF (not Dexron VI). From GM:
This information applies to 2007 and prior GM passenger cars and trucks. Dexron III is being phased out as a product name. It is being renamed Manual Transmission Fluid and carries p/n 88861800 U.S. (88861801 Canada). If fluid p/n 88861800 U.S. (88861801 Canada) is not yet available when servicing a manual transmission or transfer case, Dexron III can be used in its place. DO NOT use Dexron VI in place of manual transmission fluid in any manual transmissions or transfer cases that specify Dexron III, as a failure may result. - Thanks to Charles Krepp, TAC
I stand corrected. Here is what I found..Stupid time limits do not allow making corrections to posts... This gear oil is identified in GM documentation as a synthetic 75W-85 GL-4, Castrol Burmah (BOT 0063) manual transmission fluid, and is validated as "fill-for-life". No maintenance is required for normal operation.
When they say gm 88861801 for canada and gm 88861800 foe USA, are they talking about the same fluid or a synth for Canada?
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