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Discussion Starter · #1 ·
My 90 SPG appears to have a drain plug for the transmission fluid (looks like a 12mm allen key would do it). This despite reading elsewhere that the 90s came without a gearbox drain plug, and despite Bentley's almost complete lack of information on swapping the trans fluid.

In transmission-rebuild threads I've read, I think I've seen comments about refilling through a couple of locations, this due to the different 'compartments' within the transmission. Sorry for not knowing the exact terms but I was left with the impression that even when changing the fluid I might need to open up the gearbox when replacing old fluid.

That's my question: when I drain the transmission fluid from my 90 SPG, will it be correct to add all of the replacement fluid directly into the dipstick tube? Or will I need to open up the transmission somewhere and add a portion of the fluid there to ensure the fluid gets everywhere it needs to go?
 

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Yeah, if you have a dipstick on your transmission, I would add it there, let it settle and check the level.
 

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On my 91, I had no dipstick you could pull out. Instead, I had to remove a huge nut (17mm?) and the dipstick was built into that. It's easily visible on the right side of the transmission underneath the exhaust manifold area. I'm not sure if my tranny had a drain plug or not, but we just got a suction tool and took all of the old oil out that way. When it was completely gone, we filled it up to spec through the dipstick hole and that was that. I would suggest the same method for yours.

Also, what are you putting in there? Non-synthetic motor oil, gear oil, or???
 

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If by dipstick tube you mean the motor oil dipstick tube on the driver's side, then the answer is no. The transmission is divided inside into crankcase and transfer case. You can use motor oil in the transfer case as per Saab and Bentley, but you fill the transfer case through the plug on the passenger side of the transmission. I can't recall weather the '90 has a dipstick with tube or a hex plug with the dipstick on the end. I like to remove the back plate off the transmission to drain the fluid. That will give you a chance to look inside and see the condition of things and to clean the filings off the magnet on the back plate. You have to get beneath the car and remove about 12 bolts to get it off. Use a new gasket when you put it back on.
 

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Discussion Starter · #5 ·
On my 91, I had no dipstick you could pull out. Instead, I had to remove a huge nut (17mm?) and the dipstick was built into that. It's easily visible on the right side of the transmission underneath the exhaust manifold area. I'm not sure if my tranny had a drain plug or not, but we just got a suction tool and took all of the old oil out that way. When it was completely gone, we filled it up to spec through the dipstick hole and that was that. I would suggest the same method for yours.

Also, what are you putting in there? Non-synthetic motor oil, gear oil, or???
If by dipstick tube you mean the motor oil dipstick tube on the driver's side, then the answer is no. The transmission is divided inside into crankcase and transfer case. You can use motor oil in the transfer case as per Saab and Bentley, but you fill the transfer case through the plug on the passenger side of the transmission. I can't recall weather the '90 has a dipstick with tube or a hex plug with the dipstick on the end. I like to remove the back plate off the transmission to drain the fluid. That will give you a chance to look inside and see the condition of things and to clean the filings off the magnet on the back plate. You have to get beneath the car and remove about 12 bolts to get it off. Use a new gasket when you put it back on.
Yeah, if you have a dipstick on your transmission, I would add it there, let it settle and check the level.
Thanks, guys. My Canadian SPG has the small dipstick on the passenger side. I need to double-check the US SPG - don't remember whether it has the dipstick or not.

Concerning the huge nut / hex plug with dipstick, is this located next to the coolant drain plug (there are 2 or 3 bolts in this lower area) or is it higher up closer to the exhaust manifold? Don't want to un-do the wrong one.

As for what fluid I'll put in, not sure yet. Ammsoil or Redline if I go with synth.

I like the idea of clearing the magnet on the back plate. Plus it'll give me a chance to view the inner workings, though I won't know what I'm looking at. Still, part of the learning process. Are these gaskets readily available? Also I assume the torquing specs are found in Bentley?
 

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Are these gaskets readily available? Also I assume the torquing specs are found in Bentley?
yep and yep. I got my gasket through eeuroparts. If you're in Canada, I'd try local dealer. I believe it's called a differential gasket.

You will either have the huge-nut plug or the dipstick tube, not both. I think they both seat in the same place.
 

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Discussion Starter · #7 ·
Great, thanks Turbocon!

I'll check locally but mostly I find Saab stuff in Canada is priced exorbitantly. But maybe because it's only a gasket it won't cost much on either side of the border.

Thanks again!
 
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