Advice GL-4 GL-5 Fluid for Manual Transmission

[jkycia]

I have looked for information for the correct fluid for the manual transmission.
I know the manual asks for SAE80. I have read that I should use GL-4 and not GL5 because the synchos are brass and can be damaged by sulfur found in the GL5. I cannot find plane GL4, but have found one oil which states it is both GL-4 and GL-5 compatible.. I wonder if that would be ok or does GL-4 and GL-5 described one characteristic (for example surface tension) and not this corrosive issue. This is pretty scary. I never new about this GL-5 issue and wonder if the last time I changed the oil, I probably put in GL5..My shifting seems a bit tricky, need to go slowly carefully to make shift nicely to second gear.

Also, I only see SAE80-90, not straight SAE80. I wonder if that would be fine.

[jkycia]

I found this article. I have not read it fully but it looks pretty good.
It answers one of my questions. The GL-5 being compatible for GL-4 is
only for differentials, does not consider transmissions that have brass
synchros.

http://www.widman.biz/uploads/Transaxle_oil.pdf

[Lenny D.]

The correct fluid for manual trannys is Redline MTL (look 'em up), a superior synthetic product that observes all transmission requirements and aids in cold weather shifting problems while the unit is warming. It is also superior in finding the slightest orifice from which to leak!

The dino. recommendation is Stalube API/GL-4 85w90 sold by Napa with a CRC logo. It's been a year or more since I bought a bottle, so YMMV regarding availability.

[Mike W.]

GL5 is definitely not for BMW transmissions. MTL was long the standard but I'm not so sure anymore. I know one guy who swears by ATF, I've run 50WT motor oil in an old one, but even synthetic GL5 is way too thick regardless if the sulfur is hard on the brass or not. Really motor oil is fine, if less than ideal, but it should be a straight weight, not a multi weight.

[Pierre]

I have used Redline MTL in all my manual transmissions. It has always improved the shifting and noise level if the replaced fluid was anything else.

[Robert Bondi]

I use Redline MTL. It makes a noticeable difference for smoother shifts from
1st to 2nd in cold weather.

[jkycia]

I found a source for redline MTL and put it in. The existing oil looked light brown, not too bad I thought. There was metal particles on the magnet.
I took it for a test drive but did not notice any immediate difference. Then when I shifted into 3rd, there was this horrible noise. I was listening to it and it
did not sound like the transmission. It turned out to be a guy in a Harly laying on the gas in my blind spot. So everything is maybe fine with car. I will
look for slow leaks now.

I do have a question about the performance of properly functioning manual transmission. I am not familiar with how it should perform.
When I make a shift from 2nd to 3rd for instance, I feel like it goes through some resistance then frees up, then thunks into position. Then I release the clutch and all is fine. There this no grinding sound but I do have this point of
resistance that I have to pass through to get into gear. What is that? Is that a problem? That is what made me concerned with the oil.

[GripGreg]

You need to enter your car in your signature so we know what we're dealing with, a 4spd or 5spd.
While I'm here I'll offer my two cents; you have to go through the middle of the 'H' pattern & these are not new cars.
A bushing or grommet in the linkage my be worn or something like that. How many miles are on the odometer? Does it still work?
Someone may say it better than me. Mostly, these people have more knowledge than me.
But, please don't speed shift? It's a fun grocery getter till you make it a hot rod.
Greg

[jkycia]

This is a 5 speed with 285K miles. It had been sitting in my garage for 14 years. It maybe had this transmission issue before, I can't recall.

Yes, now I am starting to think I have a subtle problem with the transmission that I need to take care of right away. Well, subtle for me, because I did not
experience it running properly. Looking on the internet, I see
some article warning about "clutch drag".

http://www.jackstransmissions.com/pages ... s-synchros

I am not sure if it is a linkage problem, I would expect that would give me
a problem getting into a gear. I can get into all gears but I do
feel this soft resistance that I need to push through to get into gear. Never a grinding.

Now I am looking into this "clutch drag".

[Lenny D.]

You need to have all this looked at. I had shifting issues that required linkage bushing replacement. This represents components for an '80 5 speed.



View all the components and p/ns here:

http://www.realoem.com/bmw/showparts.do ... g=25&fg=05

[Pierre]

You may also have a clutch that is not fully disengaging. Where does the clutch grab when you start moving in 1st? The pedal should move out at least a third of the way before the clutch starts to grab. If it's grabbing right off the floor, you may have issues with the hydraulic system.
But my guess is the 282K miles. The transmission is showing signs of age and wear.

[jkycia]

Pierre

I just checked the clutch. Going in reverse or 1st on level ground, I do not notice it engaging until about maybe just under 3" up from the floor. It is hard to judge, ... I would say it definitely does not engage immediately but I don't think that is 1/3 of full travel.

I think that is probably what is going on though. Earlier when I was trying to understand what this resistance was, I had the clutch fully depressed. I moved the shifter very slowly (instead of my relatively firm shifting (but I am not
acting like its a hotrod) )from centre position to some gear. In this case 3rd
(I was driving on the road). I heard it catching moving gears and quickly backed away. So I think the clutch may not be disengaging and the gears are moving slowly, by shifting more quickly it jumps into the proper position. When I shift normally I do not hear any grinding, just feel the resistance.

One extra piece of information. My car was sitting in my garage unused for 14 years. When I got it going. One symptom was the hydraulic fluid (brake fluid was empty, very low). I don't know where it went. I topped it up. The clutch pedal was fully in the down position. I don't recall how I got it to pop up. ...I maybe pushed the car while in gear? don't recall. Anyways it came back up.
After that I had not problem. No fluid is leaking away.

By the way, the redline MTL I just put in to the transmission is not leaking out of my transmission..so at least that seems tight.

Jan

[Pierre]

I would flush the hydraulic system. You may have sticky clutch master and slave cylinders.

[GripGreg]

Pierre is right, and change all of the fourteen year old hoses, belts & fluids.

[jkycia]

Pierre, Greg and Lenny

Yes I agree with your suggestion of draining the clutch fluid. I will do it as soon
as I can. I planned on changing all the fluid. So far have done the engine oil,
power steering fluid, and transmission. I was about to do the differential next. Then brakes and radiator fluid.

I completely overlooked the clutch. Somehow I have never
thought of flushing that line ever. Now I see that it is important.

I need new tires. They look fine but maybe the rubber has become hard. It seems to have pretty poor traction. Yes, I need to change the belts.

I will need to check the shifting linkage if the flushing does not
solve the transmission problem, maybe change that anyways
(now wondering about a short shift kit).

This car is going to keep me busy.
Thanks for the advice everyone.

Jan