I'm having trouble finding a non-synthetic GL-4 gear oil or MTF. It seems like this is a bit of a common problem. All of the regular gear oil suppliers have gone to GL-5, and all of the GL-4 manual transmission fluids I've found have been synthetic. Does anybody have a lead on non-synthetic GL-4 gear oil that does NOT cover GL-5?

This is going in a transmission, so please no posts along the lines of "GL-5 supersedes GL-4".

I am pretty sure that CT has it, I will double check when I get home and let you know as I still have the bottle sitting in the garage.

That would be great, as it was my first stop and they had absolutely nothing that wasn't rated for GL-5 as well. If you could get me a part number, that would be awesome.

I don't know if this is still the case but I found this comment after a little searching "Unlimited supply of GL4 gear oil for lower ends of outboards at the local marine supplies."
Maybe give a call and see what they have.

I grabbed mine at CT and it was the right oil per specs on out car. GL-4 it's in gear oil section, or was there before at least.

I might give that a shot, thanks!



Was it a gear oil or manual transmission fluid? I searched both CTC stores and the Parts Source in town; all of their gear oil meets GL-5 specs..

I need fluid as well, is there a reason why we can't use synthetic?

Gear oil (motoMaster Extreme pressure) Says meets requirements for both GL-4 and GL5 was only for the initial break-in period of the new tranny.

Says made for transmissions/differentials on it. SAE 80W90

You can; I'm breaking in a new transmission, and would rather do it with conventional.



Exactly. I don't want that.

You can get the Mistu oil from Ziggy, but the price of the Mitsu oil doesn't quite make sense for break in.

I have that oil, and the price is why I'm not using it for break in

I'll throw in my leftover MT-90 if I have to, and I'm sure it will be just fine. I was just hoping somebody had a line on easy-to-get non-synthetic GL-4 that I could get my hands on relatively cheap to do a few extra oil changes before putting in "da good stuff".

I've never seen even the cheapest gear oils go for what I'd consider a 'cheap' price. In fact, most of the time Redline is cheaper than a lot of the stuff I've ever seen on the shelf at CT or Parts Source - even the cheapest stuff.

Think it was 7.something$ per 946ml on the gear oil, free with Canadian tire money

Remember that I can get most of this kinda stuff through work once I have a part number, so pricing will be pretty good. FWIW, it's now over $15/qt for me to get Redline, so even at $7 and change I'd be able to get twice the oil changes for the same price. I know our 80w90 GL-5 Pennzoil costs me about $6 at staff pricing.

In any case, I have a contingency plan, I was just hoping someone might have a line on some GL-4 that I don't know about.

I know you do. Still not a cheap endeavour, sadly...basically throwing away a good chunk of change just for a few break-in miles.

What's your contingency plan?

Also, why must it be GL-4 only and not GL-5 compatible?

GL-5 supersedes GL-4 as a gear oil, not as a transmission fluid. There are additives in GL-5 gear oils which are damaging to yellow metals (which our synchros are made from). Most GL-4/GL-5 gear oils won't say it on the back, but if you get the actual manufacturer specs, they'll specify that it is recommended for differentials requiring GL-4 or GL-5, and manual transmissions recommending GL-5 ONLY.

Someone please correct me if I'm wrong on any of the above.

I have enough MT-90 left over for one fill, which I was going to put in AFTER break-in (1000km), and change it out to Diaqueen after another 1000km. Contingency plan is to buy another few quarts of MT-90 for break-in as well.

Even using MT-90, two fills is about $75. For a transmission I just poured four grand into, I hardly consider it being "thrown away"

Not wrong just that you can look at the ingredients as that's not the case for all GL-5, from what I was reading it's the fact that they added sulfur to GL-5 and that is what damages yellow metals, but it's not in all of them. Just need to check, some of them specifically say compatible with yellow metals.

I knew the information was a bit old; I wasn't sure if they maybe corrected the problem. So I guess I'll have to do more research on each gear oil to see which ones can be used in GL-4 trannies.

A drop in the bucket, yes, and a necessity as well. I just always cringe a bit pouring out fluid I filled the car up with nary a week earlier.

I hear ya. The silvery-ness of it will probably take the edge off the sting.

P.S. I'm planning to do the 1000km break-in in two days

Just checked, turns out it is GL5 too.

Seems to be the norm. I remember doing this search about 5 years ago (for something completely different), and it took some poking around but I was able to find something I believe from NAPA. Theirs has all gone the GL5 route now as well.

Thanks for checking!

Try a truck supply store in the GTA... heavy duty gear oil... Here is what I came up with, not sure if you need to buy in bulk or go to a distributor...
https://www.brandt.ca/SiteCollectio...ynthetic/GearOil-SemiSynthetic-specs.pdf

I certainly don't mind buying a pail if I have to, but that stuff is a GL-5 as well.

Reza, do you consider there to be any downsides (other than price) with breaking a transmission in using synthetic instead of conventional? It's beginning to seem like the extra $25 I'll spend doing it with MT-90 instead of tracking down a conventional GL-4 is worth avoiding the hassle.

To be honest, I'll probably run the Diaqueen straight; I just asked about that bit because I knew you used conventional for mixing.

The pail in the link above meets GL-4 specs as well.

If you can't find anything else, break it in with straight MT-90, or whatever synthetic gear oil you can find that meets GL-4 specs. I have found regular conventional gear oil to work better than MT-90. I steer away from straight synthetics in the trans, but since your just breaking it in and not pounding or racing, I wouldn't sweat it.

After 1,000km, mix 2 parts Diaqueen with 1 part MT-90. Or mix 1 whole litre of Mt-90 with the complete pail of Diaqueen and you have enough oil for two tranny oil changes. Shouldn't be a problem at all.

I've heard that gear oils which meet GL-5 specs only meet GL-4 specs for differentials, but not transmissions which use yellow metals.

I can easily find conventionals which meet GL-4 and GL-5 specs; if you're saying they're fine for use in the transmission you just assembled for me, then problem solved

Okay so I decided to update my research a bit and taking Bryan's suggestion, look for GL-4/GL-5 gear oils which do not contain the active sulfates which can damage yellow metals. After some preliminary research pointed me to Valvoline, I called my shop's Valvoline rep for a chat. He claims that Valvoline's High Performance Gear Oil exceeds GL-4 and GL-5 specs and does NOT contain active sulfates and is therefore safe for use in all GL-4 transmissions.

I'll be tracking down a part number and ordering up a case Thanks for your help guys.

Glad to hear it!! The concoction that Reza mentions is what you will be running after break in?

That is what I run in my trans Bryan. 2 parts Diaqueen, with 1 part regular plane jane gear oil.

I'll be going with this:



with "plane jane gear oil" = "Valvoline High Performance 75w90" which is conventional.

I'll be doing the 1000km break-in on the same stuff, then might do another 500km or so again on the straight gear oil (and not driving hard) just to get more metal filings out before going to the Diaqueen/gear oil combo.

Depends how anxious I am to stretch my right leg

Hm, ok so why run this over what ever readline combo you choose?

Diaqueen/gear oil instead of MT-90? Quality and reliability.

Edit: I believe the main purpose to mixing in a bit of standard gear oil is simply because Diaqueen is sold by the gallon (3.78L), and our transmission requires around 2.6L, so you'd have to buy a gallon every fluid change. Doing a quart of gear oil and topping up with Diaqueen gets you two fluid changes instead.

Ok cool! Got you! I remember when I was shopping around for gear oil and everyone was saying the redline stuff was the way to go, that's why I grabbed the mt-85 cause I drive in the winter.

DSMers, in general, are cheap. Diaqueen is very not cheap. Redline stuff will give you a good shifting feel, so people like it and use it. My intermediate shaft bearings went from new to falling apart in about 4 years on MT-90. I don't blame it, but now that I've got a good trans I decided to go for the good fluid.

True, yeah I remember calling about Diaqueen and it was pretty expensive and at the time I called they only had the barrels.
Are you getting it from Mitsubishi?

Thanks for all the info boys, you know it's a good place when we teach each other stuff!

If you buy 11 gal you can do 16 changes but don't spill any

Grabbed mine from Ziggy. Luckily, my impulse-buying nature helped me this year; I bought most of the big-ticket items for this winter back before our dollar took a sh!t. I think I only paid about $120.

I never called Mitsu for a price, but I'd expect them to ream me. Unfortunately, not being a DSM product, the "buy it from Chrysler" trick is unavailable.





I'd almost do it just to have $1000 of oil sitting on my shelf..

It's also your recommendation when you sell a tranny Already have some in storage after I'm done breaking it in yeah, haven't done that yet :P) Fixing electricals.

and then pray never to have a house fire