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I was hoping to change my manual transmission fluid this weekend but can't find anything about the process in my haynes manual. I know those books kinda suck but I was hoping for any kind of direction on the task and came up empty. Is there an easy way to do this? What kind of fluid and exactly how often would you want to change it?

Thanks.

Lots of opinions on what type of fluid. Redline etc....
Make sure you can loosen the filler plug before you take out the drain plug !
17mm hex - allen wrench or a bit-socket to fit a ratchet wrench. I've heard in a pinch a wheel lug bolt head will work/fit. I'm guessing that there is enough of the bolt head exposed to slip a box end wrench on it or double-up two bolts on the threads.

Yes, 17mm is the correct size.
I did it last weekend.
2 aspects which might help you:
If you do it with only the filler plug side of the car lifter, you'll be able to overfill it a little bit, in case you're having a leak you want to outpace, and secondly, a piece of 4-6 feet long vacuum hose and a funnel to fit inside the hose will allow you to do a 2-person fill from the engine compartment with no trouble.
I had to remove the Redline MTL on my car and go back to 80w90. The lower viscosity MTL made the shift effort nice and low, but allowed a spun bearing kind of noise at high temperatures (around here that seemed to mean over 10 Fahrenheit.) I'm happy to be back to a quiet gear box, even though the shift effort level has again increased.

I've long been a fan of Redline, but I'm having second thoughts these days. My second G265 has gotten noisy, which could just be due to miles, but on both it's only happened after I've been using Redline. In my most recent project car, the '80 E12 with a 3.5 euro and 5 speed conversion, I used synthetic gear oil, the old GL5 type, and first thing in the morning shifts aren't as smooth, but I'm hoping I won't have any more bearing problems. I'm not ready to condem Redline as we're not talking new stuff here, but I don't really have confidence in it anymore.

As an earlier poster said, it's just pull the plugs and change it. Get a pump of some sort or some way to fill it, you can't just stick the bottle in there and pour though.

I put Mobile One 80-90W in, and am having a similar problem with noise.

Thanks for all the info. From these posts I'm leaning toward the 80-90w. Anyone else want to chime in with what they are using and how they like it?

I think that Redline product might be just great for a transmission that is still in great shape. Mine had been operated basically dry for who knows how long before I got my car. I think that my input shaft bearing may be damaged, causing the noise. There were chips galore when I removed the drain plug. The 80W90 has ceased the 4000rpm+ noise in my transmission (ok, 2500 rpm on a 80 degree day), but that's not to say that Redline MTL would cause noise in any Getrag of the day.
My advice would be against Redline MTL if there was already a noise, or already a lack of adequate fluid level in the transmission. Try the factory recommendation first, in that case, and proceed later to the lower viscosity items as a test if you have no noise problems nor leaks.
The lowered shift effort was a nice trait.

Changed the fluid today. Ended up using redline 80-90 and redline MTL mixed. Anyone else try this? The guys at Autosport Seattle called up redline And they said it was a good middle ground so I figured I would give it a shot. I didn't have any noise coming from the gearbox to start with but the fluid was low and looked pretty funky. I'll post any changes.

... hmmmm / interesting line of discussion. I'm about to try some Redline MT-90 / 75-90W ... ( somewhat heavier than MTL ) Will let you know how it pans out. Also putting new drain / fill plugs from BMW ( not allen type , but 'raised hex' ... even magnet in drain for floating debris )

Yeah my bottom plug had a magnet in it. No real change in shifting feel for me. Maybe a little better, but my linkage and bushings feel so shot I think that's where the big improvement would be. One thing that almost stopped me was the 17mm hex socket I was using plus the breaker bar ended up being 3 and 3/8ths long and it alllllmost didn't clear for the fill plug. Just something to keep in mind if you haven't been under there yet. I also used a little hand pump I got at autozone for 5 bucks and was able to do it without a second person.