This is another dumb question but, I noticed alot of you guys adding fluids to your trannies and they shift smoother. Where exactly do you drain the old transmission fluid and the new. I asked my dad and he said you dont add fluid on manuals only on automatics. So is there a place to add fluid that will help the transmission shift smoothly/ extend its life?

 

If you look at the bottom of the tranny, there is a large hex head bolt. That is the drain plug. As for the fill plug, its on the side of the tranny, about mid way up. Can't remember the exact possition of it, but I think its the only bolt on the side. Its on the drivers side. You have to use a pump to get the fluid in though. You should be able to get one at a local auto parts store.

Oh ya, you need to use 80W90 GEAR LUBE for the tranny. Not ATF. ATF will wreck it. Just thought I would point this out in case you didn't know.

 

is it a common thing to replace the transmission fluid?

 

Its recommended to change it every 80000 miles I think. I would recommend it sooner though. Gear lube isn't that expensive and your transmission is just as important as the engine, so why not change it if it hasn't been done in a while.

 

how big of pan do you think it would need? How much fluid is in there?

 

It holds 2 quarts. Royal Purple synthetic does a great job. Costs a little more than conventional tranny oil, but it's worth it.
Todd

 

Thankyou i may do that this summer sometime.

 

Just my $0.02 cents worth if I may,

I would also suggest changing your rear end's fluid as well. My Auto RX-7 that I had bought from a friend last year has never had her Rear end fluid replaced . So I went ahead bought some Lucas gear oil and dumped it in there, she takes 80/90W gear oil and I have noticed that she drives better and her LSD kicks in and grabs a whole lot better than it did before by far! When I changed her fluid it was burnt smelling and thin VERY THIN feeling. But she is all good now! So CHANGE the rear ends fluid while you are under there changing fluids as well.

-Dan

 

another quick note, don't forget about your wheel bearings. I mean if youre going to spend a little time doing your fluids, its not a bad time to think about getting some good grease on your bearings. I recommend spending as much money as you can for some really good stuff. I admit I cheated and used the stuff we use in our aircraft. Its very 'stringy' and repels water.

 

I like Redline MTL, or I mix Redline MTL and MT-90. A synthetic 80W-90W or 75W-90W that is a GL-5 lubricant can be too slipery and damage the syncro's. They need some friction to engage properly. I have been told by an old time racer that regular dino 80W-90W will work just fine as well. Royal Purple also makes a great Syncromesh MT oil.

 

i just changed my tranny fluid today on my gsl-se. It took 3 quarts . I use redline MTL fluid. It cost 8.50/ quart. Put the good stuff in there , it is worth it. shifts better and last longer. There are two plugs un the tranny. One to drain the fluid , the other to add the fluid. You will need a siphon/ hose to add the fluid. It is a bit of a pain to do it your self but , I did it today, it is done and I am happy. My 7 is happy too! And like the other guy said, change the rear end fluid too. I did it as well a week ago. I thing it took two quarts. ..have fun!!

 

the filler plugs (and maybe the drain?? not sure...) are a TAPERED plug meaning if you tighten them too much you end up spreading the drain hole bigger - so don't ream them tight!! Not necessary!
Stu Aull
80GS
Alaska

 

This is great info keep it up!

 

My favorite for manual trannies: 50/50 mix of standard gear lube and ATF auto tranny fluid. This is an old racer's trick used on cars from the 70s/80s. The ATF has plenty of lube properties, but also a lot of detergents which will clean all the crud out of the synchros and smooth out the shifting. I've used this on several cars, and it always makes a vast improvement.

 

^^ you know i heard that from my uncle the other day, and i thought it was weird since i'd never heard that before, but i might try it next time i do my gearbox oil change. ... on the other hand, how do you do a differential lube change?....i haven't checked but last i remembered i did not see a bleed hole for it, is there one? also a fill hole?

 

Yes, it is set up the same way that the tranny is. Drain plug on the bottom, and fill plug half way up the backside.

I learned about the ATF trick from a book titled "how to hotrod and race your datsun". A very good book, which covered both of the teams that were most competetive racing the Z cars, and how they prepped and modded their cars.

 

just incase. make sure you open the filler plug first.

cuz if you have troubles with it then you sure dont want to drain your fluid.

 

no i'm not having trouble with it, but i figured sure why not change the diff. fluid since i'm sure it hasn't been done since it was bought, idk, P.O. didn't know **** and he didn't do **** to it, and ...gosh it just pisses me off lol, atleast he took care of the car as far as looks go, so it's not in a bad condition besides a couple of cracks here and there from age.


i'll check that book out sometime, sounds interesting thanks, i'm always up for some new literature, yes i know i'm a nerd but **** it.

 

On preferance on gear oil, I used AMSoil Severe Duty Gear oil i believe its called. I also use it in the rear end

 

Mazda's recommended fluid change for both the tranny and diff is every 30k. Tranny takes GL4 or GL5, diff takes GL5. If the diff is an LSD unit, it needs the LSD additive.

The fill plug for the tranny takes a 14 mm open end wrench. Personally, I use a huge Crescent wrench since it has more mass to break the plug loose easier. Be sure to coat the plug threads with anti-sieze before reinstalling since the steel plug tends to corrode to the alumimun case. The fill plug for the diff takes the end of a 3/8" socket extention. This plug often rusts tight and will strip out. If that happens, the only choice is to weld an extension to the plug and hope that the heat from the welding breaks the rust bond.

 

Use redline MTL in the transmission. Be sure to use anti-seize on plugs.

 

wow, thanks that's very informative, now about the LSD, does the 85 GSL model have LSD, i don't have a jack around my house to check myself, but i was thinking the lsd came with the GSL-SE only

 

All GSLs came with lsds, if it has disc brakes, it should have an lsd.

 

yeah it's got disc brakes....hooray for LSD!!!!!

 

I will also throw my input for fluid preference. I used Pennzoil Synchromesh in the trans of my FC when I had it and I liked it quite a bit. So far since I've owned my SA(roughly 7 months now) I haven't even checked the trans fluid or the rear end fluid nor have I replaced the fuel filter(at least I bought the filter, just haven't gotten around to changing it yet)