Forgot to mention I used Royal Purple synthetic MaxGear 75W-90 in the trans. It says GL5 and GL4 and safe on yellow metals and synchros. I couldn't find any GL4 gear oil locally, only GL5 and this was the only one that said safe on yellow metal.

Now I'm starting to think that maybe it isn't so compatible...??

Today I check all local stores and found Pennzoil synthetic 75W-90 GL4 at $15.97/qt or I can get the "proper" GM spec 12346190 (from tracker manual) from the GM dealer for $29.97/qt.

Not sure if the fluid change might buy me some time before overhauling the trans...what do you think?

Dean

 

I had the Amsoil gear oil in my Sami trans after a rebuild last year, just chanced it and went back to the plain ol' GL-5 80-90 and it shifts noticeably better. ymmv

 

Did you mean plain ol' GL-4?

 

I wish I did, I REALLY like GL-4 for these old dogs but sadly there is no availability here. I just drained out the Amziol GL-4 synthetic and was surprised by the GL-5 giving notably better shift quality. If you know where to find non-synthetic GL-4 I will be your best friend! haha

But seriously, do you know who sells standard GL-4 off the shelf?

 

No I don't know...that was my problem, couldn't find any "plain" GL4 anywhere.

 

I think it's possible Motorcraft may have some for a premium price, maybe Ford stealership. I was actually surprised that the GL-4 Amzoil did not offer better shift quality than the no name Carquest GL-5 (stated safe for manual trans on the bottle). I'm thinking that the Synthetic part might be the issue for these transmissions. I'm still hunting for some GL-4 to try and compare shift quality with similar ambient temps.

 

That's what I'm hoping is the issue with mine. Just not sure what lube to get. The royal purple was a cross reference to the gm 12346190 that was in the manual but not sure now if it "really is" compatible. I'd like to try something else just not sure what. At $40-$60 per "try" it gets a little expensive.

 

that's the problem, nobody around here seems to have conventional gear oil in GL4. Even that GM 12346190 that is called for in the owner/maintenance manuals is synthetic according to the local dealer.

 

I think Big Ed explained it perfectly, inadequate friction from slick fluid lacks the braking effect on rotating masses, I have heard it explained this way before and it makes sense. It has less to do with the viscosity and more to do with friction modifiers, or lack thereof.

I tried the fancy fluid in my 2005 Saab 9-5 5-speed manual and it helped an innately notchy gearbox shift better. For any older vehicle I'll be using whatever was recommended. I'm still looking for a place to buy.

Our Suzuki vehicles take such a small amount of fluid and it can stay in a while that the extra cost of honest true conventional GL-4 is inconsequential.

 

Oh yea, just had a conversation with a parts guy. Sometimes the "old" numbers get superseded as availability starts to wane, I understand the same is true for fluids. So the old GL-4 may have been superseded to the newer GL-5 and the old number pulls up the new product... maybe.

I will call Ford and if no luck GM tomorrow and see if the local dealers have some honest dino GL-4 left.

 

I'm running lucas 80-90 or 85-90 dont remember which atm (still half asleep) it took about 2-3 weeks after the install before it shifted smoothly from 1st to 2nd but now its like butter downshifts are still a lil stiffer than I'd like them to be but over all I'm happy with it other than the price =P $17 per qt

 

I bought Redline MT90 for my tranny. It is GL4 rated. A little pricey, found it for $14.50 a quart on ebay. I have not tried it yet but my son changed out his Jeep's fluid and it smoothed out his shifting both up and down.

 

This is what I have so far:

All local auto parts stores are bingo on this stuff but are very ready to let you know that GL-5 is retro-compatible with GL-4 applications... sure it is...

GM still makes it but prices seem really lofty and of course to get it you would have to contribute to the delinquency that is GM. Buying anything GM ranks on the pleasure-meter right up there with shopping at WalMart.

SOOOO I have done a great deal of searching online and off and found that many older car forums sing praise to the Motorcraft conventional GL-4, many recommend veering away from synthetic or blends for older gearboxes, which is consistent with my experience so far. Some of the newer Gearboxes apparently react well with the synth or blend GL-4 but that doesn't appear to be us.

I found the part number on Vintage Mustang site (Motorcraft XT-4-QGL). Calling Ford dealerships asking for GL-4 is an exercise in futility, until you are armed with the part number.

Motorcraft XT-4-QGL is a conventional non-synth no bovine feces GL-4. The GM versions were hard to tell, looks like most of their GL-4 is synth, judging from the prices I would say that once you open the case a hooker will jump out and dance for you.

I just ordered some of the XT-4-QGL from my local Ford Dealership. He to was stumped until I produced the part number. It is listed in their books as an additive but is actually just plain jane GL-4. A couple of the forums forewarned that it would show up as an additive in their books.
He had one qt in stock and is ordering me 2 additional qts which I will see Monday. $12.81 a qt.

I will post follow up once I have put it in and used it, and again after a few hundred miles.

I hope this is useful for those looking for straight up GL-4. I'm glad this was brought up again as it prompted me to revisit getting the right juices for my vehicle. Also please be advised that my vehicle does have a freshly rebuilt Samurai trans mated to the kick engine.

 

Ok, thanks everyone for your input. I decided to just get the recommended fluid - from the owner/service manual. I ordered GM 10953477 which is the number to use in Canada - in the US it's GM 12346190. It is costing me $29/qt..like gold. I figured I paid $25/qt for the royal purple that's in there now so what's a couple more dollars.

My reasoning was, if I try anything else and still can't downshift then I'll wonder if it's the oil again and probably spend the $29/qt just to try the gm stuff anyways so might as well just bit the bullet and use what the manual recommends.

If it still gives me problems, then I guess I'll just have to rebuild the trans...hopefully that holds out until next winter - only drive this in the summer.

Dean

 

Update:

I got so busy with work I forgot that I orderd the GL-4, so when I showed up at the Ford dealer I was not surprised to spot the 3 red bottles I ordered sitting on the pickup desk behind the clerk.

Pics attached with part numbers of the items. Again they list this as an additive but it is actually just straight up non-synthetic GL-4 with no GL-5 flavors at all.

Pics attached with part #.

I'll be changing the fluid this afternoon and after I run a few miles I'll update the results. I hope this helps those searching for straight up GL-4.

From what I have read and heard this is the fluid of choice for many makes/models with older manual transmissions.

 

Thanks for the heads up, I'll have to check with the ford dealer to see what the price is like up here. Got to be cheaper than all this synthetic stuff I've been finding

 

I would think so to but I have heard and read many times that the shift quality will gradually change with the change of fluids so I figure a handful of trips to work should leave me in a place to offer an informed summation.

I am optimistic as even going to the GL5 from they synthetic GL4 made a difference I could feel.

 

Just an update on what's happening. I replaced the royal purple gear oil and replaced it with the recommended GM manual trans oil. I drove it to work and back a few times - about 50-60 miles and although I can now upshift to second (better than before) it still won't downshift into second. Also, when it warms up, by the time I get to work, it won't downshift into any gear. I have to coast into the parking lot and just before it stops rolling, I can shift into 1st and park.

Pretty much had it with this so tonight I took a bit of a drastic measure and drained the oil and filled it with varsol and ran it through the gears (just at idle) on jack stands for about 10 minutes and then drained. I'll let it drip overnight and then put the proper fluid in tomorrow. Worst part is, it shifted nice up and down in all gears with the varsol in there...

My thought was maybe the synchros still had some "slippery" royal purple in there and this flush might clean it all out before the oil change...fingers crossed...trying to postpone a rebuild

Dean

 

FWIW:

During my road rally days, we used straight ATF in troubled trannies....

..... Philip

 

I filled it up with proper oil and took it for a test drive...still the same. Upshifts are ok but won't downshift into any gear. I guess I've done all I can with this one - time to shop for a replacement.

 

In a pinch, you can learn to double clutch....try it and see if it works - clutch in, shift to neutral and let the clutch out - then rev the engine while in neutral, clutch in, and downshift. Just like your granddaddy did....
Example of it here:
Skills 101 – How to double clutch | Hemmings Daily

 

Trans refilled with GL4, It shifts better than ever, still slightly notchy with the high RPM 1-2 up-shift but that's splitting hairs. It finally feels like the fresh transmission that it is. The more I drove it the smoother it got, WELL worth the time and $ invested.

I'm glad I got enough GL4 for the next trans service as well.

 

I was in NAPA the other morning. On the shelf:

Sta-Lube API/GL-4 Gear Lube. (Dino type) 1 gallon, $37.09.

Same stuff I use in my transfer case(s).

 

Here's another update. Last night, I dumped the trans fluid and replaced it with ATF as a last attempt...drove it to work today and it shifts great, just like before I started with all this fluid change stuff. I upshifts and downshifts nice and smooth now. Now what? do I keep driving it with ATF? it's the only thing that's worked so far. Might try that GL4 (ford trans oil)..not sure.

 

I drove an S15 for 500k with ATF, running hard and 4x, dive rescue with 1200lbs of dive gear in back... Some times hauling boat....

... Philip

 

that's reassuring. I only put on about 2k km per season...should last me until the winter then I'll go through it then.