DONNA

have read about the wonders that "GM synchromesh" fluid does, and want to fill my 85 with it,,,,i believe it takes 1.8 qts,,,can you add the fluid from inside the car, do you just remove the gear shift? , are there any springs or stuff to watch out for....? do you top it off or fill only the amount that the specks say,,,and do auto parts stores stock it......thats all...

jutny

i am also VERY curious about this, because it reminds me i havent changed the tranny fluid since i got the car (who knows when it was changed)...

what are the benefits of the GM Synchromesh as opposed to normal gear oil?

1st to 3rd

The gear shift comes out with no problems (no springs to go flying, etc.)... but it will not help ya here.
The easiest way is to buy a pump and a short length of hose from the autoparts store. For a couple $ you can get one that screws onto the top of the lube bottle. Make filling the tranny and rear a snap.

peejay

I thought to check my trans fluid yesterday when the weather was nice. (AKA not precipitating and a balmy 45 degrees) Glad I did, durn thing was nearly empty. Guess it needs to be resealed.

I tried dumping into the shifter. No dice. There must be a seal in there... oh well at least the tower's full. So now I have a mostly empty bottle of Mobil Synthetic gear oil (left over from my Subaru days) and no way of getting it in.

Took a length of clear plastic hose, heated one end with a lighter, and jammed it over the tip of the Mobil squeeze bottle. Now I just need fluid. Remembering something John De Armond posted years back on the hotrod mailing list, I rummaged in the back of the garage and got 2 quarts of.... Dexron ATF! Topped the bottle off, carefully squeezed fluid in. I was able to only get about 1/2 quart in at a time before I had to refill the bottle, but IT WORKED.

I've drove the car for roughly 30 miles now. The trans definitely likes being bathed in ATF. The bearings mostly quit whining, and the synchros actually work!

I have a strong feeling Redline MTL is just synthetic ATF with a different label. If you think about it, the conditions that the gears suffer in an automatic transmission are much worse than in a manual trans... manual trannies have much larger gears and bearing surfaces, and the friction modifiers work equally wekk on brass clutches (synchros) as they do on "organic" clutches (clutches/bands in automatic).

mwpayne

My tranny was really notchy, but the fluid looked like it had never been changed. I did it the hard way, drained it from the bolt on the bottom, the ran a hose in the inlet on the side (be sure to take that one off first!! Don't want to drain it and then not be able to get the bolt off to fill it)
I jammed a small funnel onto the hose, slow but sure process to add a little GM syncromesh, let it drain, add, etc. The syncromesh really helped smooth out the tranny. It's hard to compare, but it made more difference in this tranny than redline did in another RX I used it in.

Conway

Actually, you can fill an SA tranny through the shifter hole. Learned the hard way that the FBs have a remote shifter.

Is ATF really good for your manual tranny?

Conway

Randy Nix

1st to 3rd has the right idea. I just changed my tranny and rear end fluids last weekend. The screw fitting and hose for the gear oil bottles worked great except the hose was about 2 feet long and I needed 3 feet. I used a piece of clear hose and put on the spout at the end of the tube to extend it. To fill I came in from just below and to the right of the oil filter, around the starter and into the side fill hole on the tranny. The nozzle has a cut off which helps a lot and I would recommend getting one from your local parts store. To drain the fluid after the hose is in place I took a knife and poked a hole in the bottom of the gear oil jug (after its upside down of course). This lets air in and it drains faster. I used Mobil 1 synthetic 75w-90. Shifting is better. Gas mileage increased from 23 to 25. Seems to run much smoother.

jutny

w00t

yes, makes my job really easy then

pratch

I used the IV method until the most recent time when my buddy Carl introduced me to the wonders of the $10 pump. It's worth every penny since instead of spending 15 mintues setting up your IV drip, you just squirm in and start pumping.

peejay

600 miles so far. Transmission LOOOOOVES Dexron.

The conditions in an automatic are much harsher than in a manual... all the gears and bearings are under more load since they're lots smaller, not to mention that the fluid is much hotter as well because its main purpose in an automatic is as a hydraulic fluid.

Pele

iTrader: (28)

My dad's Volvo uses Type F ATF in the manual tranny.. Although the Overdrive is hydraulic and automatically engaged... Weird, huh.

Use an old Lotion Bottle or Bathroom soap pump if you're cheap...

Here's a creation, great for filling multiple cars if you have them...

Take a large bottle, a gallon works well. Preferably with the squeeze nipple on the end, otherwise, drilla hole in the lid and attach attach a hose to it. 6 feet of hose is good.

Great... Now you have a bottle with a hose. If you turn it upside down, it will dispense through the hose... But when the tranny or diff is full, you'll spill it all over the place while crawling out of the car to turn the bottle right side up... Well, you can bend the hose off... Or you can put a valve on the end...

Attach a hook to the bottle (Coathanger works well) and you have a nice IV for your car. Hang from the glass hatch latch for filling the differential, and the hood latch for the tranny...

Keep several around. One full of ATF... One full of Gear oil... One full of Limited Slip Fluid... Whatever...

Wonder what happens if you fill the Tranny with MMO?

peejay

I wouldn't try it.

MMO is more like a light grade 2-stroke oil than a lubricant for heavy machinery. I'd burn it but not protect any bearings or gears with it.

Cloud

I'll be swapping in Redline into my million mile GSL tranny today...I'll let ya know how it goes. I plan on just using my Mityvac to pump the fluid in, same as I've done on a ton of other cars. Hoping it gets rid of some synchro whine!

peejay

Synchro whine is due to your needing to repack your muffler bearings. Also check the blinker fluid, it may be low due to a leaking connuter valve.

Pele

iTrader: (28)

I know... I was messin.

jeremy

iTrader: (1)

i thought atf was bad for many manual trans due to some ingredient or cleaning agent eating away copper synchros.

Wankelguy

I'm afraid I have to take the blame for that bit of misinformation. My RX3, RX4, and SA all were filled through the shifter hole, but evidently the remote mounted shifter on the FBs doesn't allow this. Sorry for any inconvenience this may have caused.

I've had fantastic results with Amsoil 75W-90 in my transmissions. It even cleared up my skritchy 3rd gear synchro in my RX4. Seems to me that if ATF were good to use in manual transmissions, everyone would be doing it. -WG

fatboy7

ATF seems way too thin.... I can't imagine that it would protect the more 'open' manual transmissions. SAE 90 is like sludge in comparison.

DriveFast7

iTrader: (1)

ATF in a manual tranny? That stuff is thin. Can it handle all the gear meshing of a manual trans? With my 74 REPU with an abused trans I did fill it with MT-90 and overfill it with .75 quart of Redline Hight Temp ATF. It does shift *real good* and is quieter. We might be onto something here.....

I've always had good results with redline MTL or MT-90 in manual trans. Smoother shifting and quieter.

Just to stir the pot, some racers use Lightweight Shockproof diff oil in their trans!

peejay

Why couldn't it handle the manual trans?

jeremy

iTrader: (1)

atf doesn't contain friction modifiers to help the synchros "grab". also what i posted up a few.

jw36

I won't test ATF on mine but GM uses it in a lot of their transaxles.

inittab

Now that's a testament! The synchros in those early RX trannies were delicate to say the least.

peejay

Actually, it's gear oil that doesn't have frictiopn modifiers, and ATF that does have them. Remember all those clutch packs in an automatic...

Critoris

So, what's the concensus here? For those that have used ATF, what spec should I look for? I know I can use 75/90 gear oil, but what's with the GM Synchromesh? Do you add it to oil or fill with all Synchromesh stuff or what? I know how to fill it, just what is everyone using?