JJ'89

I used Sta-Lube in the 4spd Muncie and the Positraction rear axle in my '65 Chevelle, back in the 60's and 70's. GL4 for the trans and GL5 for the axle. I topped-off the gear drive in my roto-tiller yesterday, GL4. I buy it at a local hardware store. The big chain auto supplies probably don't carry GL4. Sta-lube is OK. You can pay more for a name and glowing testimonials. I won't.

Charchee

Hey, it's answers like that one that make you one of the great ones. These oil grade / brand discussions can go on for a dozen pages. That one sentence pretty well sums the whole thing up. Makes perfect sense. Based on that, I'll fill mine with GL-4 at my next change.

Harold Of The Rocks

I've read this thread over a few times, and the linked paper discussing GL4 vs. GL5. Great insight and I've learned more about oil then I thought was possible. It also prompted me to visit my local auto parts store. No GL4 available, only Gl5. Also looked into the 93 FSM and it suggested GL5. It seems almost counter intuitive to run oil that auto parts stores and the FSM don't list/carry. However, on what I've read here, I'm sold on the GL4

Hammel

I don't get to drop in to this forum quite as often as I'd like, but man when I do... The subject may get discussed extensively but I am very glad it does. Read all the posts on here. Checked and read links. Now to buy the oil. My question for you all though is, on a 13 tundra with nearly 100k, what would you lean towards? gl4 or 5? TIA

spddm0n

I found it interesting that the Toyota FSM's (the 1988 and 1993) calls for GL-4 or GL-5. Typically, I trust Toyota without question. The manuals sometimes have misprints, but other than that I expect they know what they are talking about. As I begin to think back, I'm trying to remember where I decided that I needed GL-4 (other than my Nissan Xterras). I build 2nd gen Toyota MR2 Turbos too, and now I look back at the FSM, it also calls for Gl-4 or GL-5. ??

Hmmm...Was it somewhere later down the road that someone determined the GL-5 additives were damaging the yellow metals? Was Toyota NOT aware of this, or are there simply no soft yellow metals in the manual transmissions (transaxles)? I'm a little surprised that Toyota would suggest either was ok to use, if it wasn't. I do remember when we started using a higher performance oil (Redline MT-90), that the GL-4 conversation came up. Perhaps that was the beginning of the conversation - almost 20 years ago.

I have a later model E-153 from a Toyota Solara in my MR2, and I opened and built that one myself, but it was forever ago and I don't remember looking for soft yellow metal parts. I can't find the FSM for the Solara, but I imagine it also calls for either GL-4 or GL-5.

I'll also continue to use the GL-4 for now, but...interesting discussion...

millball

GL-5 spec oils offer advantage in hypoid gear differentials, but their enhanced slickness is not needed to lube the helical gears found in trannies.

That enhanced slickness is sometimes found to make worn, hi-mileage syncros less effective, which contributes to more trouble when shifting at mismatched engine/tranny speeds.

If it were my truck, I'd use the GL-4 in the tranny and GL-5 in the diffs.

Although I do run all mine like this, syncros don't really matter that much to me, because I double-clutch 'em all like they were sliding gear crashboxes anyway. Old habits are hard to break.

nathansarli

I have a 93 pickup V6 4X4 5spd that is beginning to have some transmission issues as it occasionally comes out of gear when I stop on a slope. I'm currently running Valvoline Synpower 75W90. Is it possible that running a different fluid might fix this problem?

millball

It is very unlikely that different gear oil will help, or solve your issue.

Trannies that won't stay in gear usually require overhaul. Your issue might be due to several potential faults including, excessive main or countershaft endplay from worn bearings, bent, or worn shift fork, worn or damaged syncro or sliding dog... ect. Sorry.

millball

I would remark that back in the late 1970s' or very early 1980s' when I was building and running air cooled buses and bugs, VW was warning against the use Of GL-5 spec oils in their transaxles.

This was more than 35 years ago.

Charchee

May be based on application. I know a Caterpillar machine's maintenance manual will show upwards of five different recommended fluids for an axle or transmission based on temperature, ground speed, and load conditions. An excavator that normally uses HYDO-10 hydraulic oil is recommended to run 30 Weight Diesel engine oil in the hydraulics if it has a hammer pinned to it.

I would imagine the GL-5 would be the fluid to use if you were pulling a heavy trailer down county roads at low speeds in a constant third gear type application, while GL-4 would be the stuff for city driving where you are shifting every 15 seconds under no additional load.

fdp101452

I'm not taking a stand on either gl4 or gl5, but I find this whole thing interesting. My 90sr5, I suppose came with gl5, I don't know that, I just suppose that it did. I do know that for the last 20yrs it has had gl5 in it. The pickup now has 200k on it and it still shifts fine. I live in a small town with lots of stop and go so it gets shifted lots. I would think that by this time and miles that if gl5 was a big problem, I would have that problem and I don't seem to. I used gl5 in the past because I had never heard of this before. I intend to use gl4 the next time I change it based on this. Your thoughts?

Harold Of The Rocks

As a few folks have said, it all comes down to personal choice. I've taken heed of this discussion and will go with GL4 during my change. If it doesn't work for you, or if you feel it isn't worth the increase in cost (gl4 is expensive), gl5 is still readily available and inexpensive.

gsp4life

My guess is that all auto parts stores used to carry gl-4 gear oil back when more cars had manual gearboxes. I know Pennzoil used to make one, don't know if they do anymore.

I filled with the Sta-lube stuff and have no complaints. Got it for $25/gallon at napa. I've read multiple stories that it wouldn't shift well at freezing temps, but that wasn't the case. Had it running down to 20° which is the coldest it got this winter and had no problems to speak of.

For comparison purposes I've also ran the much more expensive gl-4 Redline 75w90 and didn't think it performed any better than Sta-lube.

Harold Of The Rocks

Indeed that Redline is expensive. Did you run it just in your manual transmission or in your diffs and transfer case as well?

gsp4life

Just in the tranny. You always want gl-5 in the diffs, I forget why at the moment but possibly cause of the extra pressure additives. I had a cheapo gl-5 in the t-case cause it doesn't care what you use. I did read about the potential for mixing, but when I drained both to replace with Sta-lube, the fluids we're still individually red (redline) and yellow (cheapo gl-5).

RJR

Bevel gear teeth, such as are in your transmission or tcase, are shaped so as to roll across each other when they mesh, with little sliding. On the other hand, the hypoid gear teeth in your diff ring and pinion slide across each other much like a worm gear system. Plus the tooth pressures are higher because the gear reduction is greater at the diff than anywhere else. So the diff needs GL-5 for lower friction and higher pressure capability.
Depending on the tcase model, it may care about what you put in it. The gear driven cases don't care, but the VF1A chain driven case behind the R150 manual tranny has synchronizers to allow for on-the-fly shifting from 2wd to 4wd, and from 4lo to 4hi (but not the other way around). Those synchros will work better with GL-4 in there.
There are oil seals (two, I think) between the transfer case and the transmission, so there shouldn't be any mixing of fluids.

irv

Good to hear. I just put a W56 transmission with 150k on it into my 86 pickup and I filled it up with Sta-lube. Shifts perfectly fine to me so far. I live in Maine. So we'll see how it does come winter.

gsp4life

It should be fine. I know you guys get a few minus temp days up there so it might be slow for a minute or two when it's that cold. Do you know about the transmission warm-up trick? Put the t-case in neutral, tranny in 1st and just rev around 2000 rpm for a minute. I had no need to do this myself, but someone on yotatech mentioned it awhile back so thought I'd pass it on.