Transmission Fluid
 

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 :eek: . 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 shit and he didn't do shit 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 :D thanks, i'm always up for some new literature, yes i know i'm a nerd but fuck 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!!!!! :lol: :lol:

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 :bottom: nor have I replaced the fuel filter(at least I bought the filter, just haven't gotten around to changing it yet)

what do you guys recommend for the diff. i've read lots of tranny recommendations but hardly any diff. ones.

tranny and diff take the same thing. The only difference though is that if you have an LSD make sure you add some LSD additive in there or make sure what you're getting already has it in there

Yep, or if you're using something like Synchromesh in the trans, just use a standard gear oil in the diff with the additive if LSD eqipped or a good synthetic in which you wouldn't need the additive

I like the Redline Heavy-Duty Shockproof fluids.

I bought the Castrol Hypoy C gear oil it has a label that says limited slip performance do I still need to add the LSD additive that I bought?

"If it ain't broke, don't fix it."
 

A lot of today's lube oils have the friction modifier already in them, so no additive is required. If it is labeled for limited slip you should be good to go.

Been thinking about changing the differential fluid in my Montero, but I hate to throw away perfectly good fluid. I know it is good fluid because it has 325,000 mile on it, the limited slip still works and it is quiet, so I am tempted to just leave it alone.

I have owned a lot of 1st gen RX-7s and have gone as far as 180k miles on them, never changed trans or diff fluid. I have never had any trans or diff problems with any of them. I do put magnetic plugs on the fillers, and so that gets checked regularly. I should mention that I also have several FB trannies and LSDs in my shop, just in case.

I have a friend who has made his living working on Mazda rotary cars since 1970, and his comment about all this was "If it ain't broke, don't fix it."

I do change engine oil on all my cars at 4k miles.

I used Royal Purple when I installed my LSD rear end. It states that no addative is needed, but I had quite a bit of chatter with it. I added a tube of the lsd addative, and haven't had any issues since.

^That's what I was looking for Kentetsu. I just put AMSoil in my rear end and tranny, but the rear end still chatters and the tranny actually shifts worse than it did before the change. Even with the clutch to the floor second gear still gets caught up. Perhaps the synchro is on it's way out. I'll try adding some LSD additive to the rear and some ATF or Synchromesh to the tranny. Maybe that will help

all went well so far. I put the Redline MTL in the tranny and i ended up adding the LSD additive for good measure to the rear end.

REDLINE MT-90 FTW it has cured grinding syncros in many of the cars that I have owned. I use Redline 75w-90NS in the rear end with redline additive. nothing better. I have used royal purple in the rearend and it's just as good.

I can vouch for this. Tried it in a tired old S2 tranny that I needed to use temporarily. It was pretty much impossible to shift into second without it grinding horribly, and getting it to shift at all took some skill. Long story short, I'm still using that tranny and the only reason I'm planning to change it is because I want to upgrade to a TII unit. After giving it that treatment, second gear doesn't grind at all unless I really slam it (though I do still have to be careful when downshifting).

You actually drained out some of the 80/90 and poured some ATF into that tranny? I don't think I added any when I filled it up last year, after changing the front seal and cleaning out the broken gear chunks. :)

If I remember right you put a mixture in it the first time because you didn't have enough 80W-90. Later some of it got drained and it was replaced with straight 80W-90.

Oh yeah! The ATF was diluted a little but you are correct. That means it still has perhaps a 50% mixture in there, or close enough to have improved the driveability so noticeably.

I had to drain some out to take the front hub off in order to change the seal, and I recall it was quite red as it came out.

It's actually quite pleasant to drive hard and shift it fast, yo. :D A major improvement over when it was in the blue car (constant grinds), and over what was previously in the white car (noise city).

Who knows... it may live for a long time behind the turbo.

I use 75-140 in my racecar in both the trans and rearend. Usually use Amsoil but have Royal Purple in the trans right now. I change it once a season or as necessary when making repairs. The heavier weight helps deal with the heat generated in racing - the trans shifts better at the end of a race. Not necessary on the street. I won't use dead dino oil - not worth the cost savings

Not sure about the ATF mix. I'm pretty conservative so I tend to follow manufacturer recomendations. So, I am not sure I would experiment in this way but what the heck - thinner lubes don't suck up as much power so at least it will feel better for awhile. Frankly it has been my experience that you can't hurry a shift in a Mazda gearbox - just ruins them faster when you do.

Get one of these to make the job easier

http://automotive.hardwarestore.com/...p--648771.aspx

I have seen them at autoparts stores too. They fit Amsoil containers the best.

I always use teflon tap on the trans fill plug and the rear end plugs. Seals them and makes removal easy.

Thanks for posting up the positive results on the ATF. Most people look at me like I'm crazy when I tell them to use half ATF in their manual tranny.. :)

In case I didn't post this earlier, this trick comes from the Datsun Z race teams who swore by it. Information came from the book "how to hotrod and race your Datsun".

redline/royal purple vs valvoline
 

How much are redline/royal purple compared to valvoline?