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I am going to change the fluid on my tranny. I'm sure people have a preference on which type of oil.
I want to: 1) Change the fluid 2) Replace the lower drain plug and gasket because the hex is hammered on the nut.
Where do I go to get a manual tranny drain plug and gasket? . . What size are they?
Finally, I can fill from the top right? I was reading some threads about people complaining about filling from the bottom and was wondering why can't I fill from the top through the gear shifter and replace the shifter bushing while I'm there?
Someone correct me if I'm wrong but the gear shifter has no fluid path to the case. Meaning the fluid in there doesn't drain down to the case, it stays put. You have to fill via the check plug. As for oil I've used and liked Royal Purple.
You definitely can't fill it through the shifter. Although, it's a good idea to take the shifter out to make sure the shifter housing is topped up as well (fill until it just covers the top of the shift block).
There is a factory fill plug with a square head on the side of the transmission, so as long as you can crack it loose you're good to go (check that you can loosen the fill plug BEFORE you drain it, of course).
Actually getting the fluid in there is a pain. I usually take off the shifter boot and run a tube down from there. Under the car I put the tube into the fill hole, and then on top I put a funnel into the tube and pour the fluid down that way.
Otherwise if you have a fluid transfer pump that's an option too. The transmission is full when it starts to drip out the fill port.
As far as fluid, I've used Royal Purple with good effect. Later I used Canadian Tire store brand synthetic gear oil, it feels about the same as RP. I think the important part is that it's full-synth, brand is not that important.
I find conventional gear oils make our transmissions a bit notchy. Well, more than normal anyways.
Certainly cannot fill from the shifter extension. get under the car and loosen the FILL plug first (the higher one..) this is to ensure you can always re-fill the trans.
Loosen the lowest (drain) bolt. I'm sure this can be purchased from Mazdatrix or Atkins rotary.
I prefer to use a GL-4 type fluid for the older soft syncros in these transmissions.
2.2 or 2.3 QUARTS OF REDLINE MT-90 GL-4 SYNTHETIC TRANSMISSION fluid is what I used in my S5 NA trans.
drain plug washer is 9956-41-800, the 4 means its aluminum (2 is copper) and 1800 is the size, 18mm ID
i made a little thing last time, that goes into the fill plug area and then attaches to a hose and then a funnel in the engine bay, so it was really easy
"GL-4 is suitable for hypoid gear service when they are under severe service but are without shock loading. GL-5 is suitable for hypoid gear service under severe service and shock loads and not for use in a gearbox"
I use Red Line MT-90 75W90 full synthetic gear oil. Its recommended for GL-1, GL-3 and GL-4 applications as well as where most special synchromesh fluids are specified.
I also use a suction gun to transfer the gear oil to the gearbox. Your local farm store (i.e., Tractor Supply Company) sells them for about $15. (https://www.tractorsupply.com/tsc/pr...y?cm_vc=-10005)
I must admit, I love the suction gun. . . .. Was looking at hand pumps and they do 5cc or 8cc pumps. . .. .The suction gun would be much quicker and might allow the use of a longer hose.
02-20-22, 11:57 AM
