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Discussion Starter · #1 ·
Ok, I filled my transmission with Mobil1 synthetic gear oil. 75w-90. This is what the guy at the auto place said to use, but my friend who works at a oil change place says thats crazy. Did I put the right stuff in, or did I just screw up my transmission? Thanks in advance!
 

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Wasaabi, i wouldnt worry about doing damage by using a heavier oil, i'd be worried about trying to shift...

if i were you, i would drain that 75w90 and put in something much lighter, microcat36 recommends 10w30 or 10w40, as does the manual on my '92 900T (manual) but i am currently running 20w50 full synthetic.

somewhere colder than southern california and i would be running 10w30 myself
 

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Wasaabi, I'd recommend that you drain that stuff out. The synthetic that Saab uses is a special formulation that has an additive that increases ASTM bearing strength. Mobil 1 and regular synthetics are designed to "roll" and the Saab oil is designed to "slide". "Rolling" oils do not support the forces found in the 9000's crown gear, which has sliding friction engagement and very high bearing stresses at the interface, and don't have the bearing strength of fossil oils. All 9000's came with fossil oils, until '98 which was the 1st year, IIRC, that the transaxles came from the factory with their own synthetic blend. It's anecdotal, but I've heard that many from Saab Engine Development considered Quaker State 10W-40 one of the best oils to use in a 9000 transaxle.
 

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Discussion Starter · #6 ·
Just before I came back here to check for responses to my post, I read about the mobil1 gear fluid itself. And in the depths of the detail sheet it said "not for use in manual transmissions where motor oil is recommended."
I hear that the 91-92 gearboxes lack a drainplug!
I think I've got 2 choices. 1) remove the transmission and drain it out the way it went in. (Really not as painful as it sounds, I'm in the middle of a 5 speed conversion, which should explain my ignorance about fluids ).. 2) A friend has suggested siphoning. Would the synthetic gear oil cause the transmission to kick the bucket way before normal or are we talking 10k miles or so?
 

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I hear that the 91-92 gearboxes lack a drainplug![/b]
if there is no drain-plug i suppose siphoning would be the next logical answer

Would the synthetic gear oil cause the transmission to kick the bucket way before normal or are we talking 10k miles or so?  [/b]
i would expect no trouble at all from running synthetic oil in a manual transmission. as i mentioned before, i run 20w50 full synthetic in mine

there is another thread with discussion about engine oil, The Great Oil Debate in the Saabscene:performance section. i think you may find some useful information there.
 
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