More gear oil

[Drainx]

Well I have been having people tell me my synchros (5spd all-trac) are dying from all the crunching my transmission does when I shift into 1st, 3rd, 5th. I changed the clutch slave cylinder and I hoped it might help fix the crunching as well, it didnt but Im not too upset about that. So, I decided to try changing my gearbox oil as I have no idea when it was last changed and I havent ever checked on it. Might have been replaced ~50k miles ago from previous owner replacing engine. Forum searched, I already know it needs GL5 oil in the gearbox anyways. I do like what I hear about this Redline 75W90 NS GL-5 Gear Oil. Now without going out of 50 miles to get 5 litres of this stuff IF theres a store that even has it in the first place, are there any alternatives just as good or almost as good and cheaper as this Redline 75W90 NS stuff that I might find in a smaller town auto store (autozone, oreilly, advanced autopart)? I just want to get something just as good or almost as good here in town and not have to rob a bank to pay for it. Or is ordering it online and waiting a few days better idea?

[SuperRA]

Sorry I can't answer your question for an alternative. I just wanted to say that I used Redline MT90 to fix some hard shifting and it worked. I've been driving it for almost two years now and the shifting, when I bought it, was bad enough to get $200 knocked off the car's selling price. Of course depending on your particular problem, it may or may not work for you. I don't know how the 75W90 will perform.

[Drainx]

I think its weird the manual says for the all-trac use GL-5 multipurpose gear oil and the FWD use GL-4 OR GL-5 multipurpose gear oil. Thing is, I cant make heads or tails of most the cheaper stuff (under $10/qt.) at the auto store on which has the slippery LSD additive I dont want (?) in the gearbox. Some specify they are for LSD, but others contradict themselves when they say its for manual gearboxes but have the limited slip additive.

[Flashmn]

I do like what I hear about this Redline 75W90 NS GL-5 Gear Oil.

GL-5 is harmful for yellow metal synchros. Are you sure that the GL-5 isnt just for the transaxle that transfers the power from the engine to the rear axle and not for the entire gearbox?

[RogueMoog]

For the manual tranny All-Tracs, use gear oil in the rear differential, tranny, and transfer case. The latter two are connected, I believe, and I know there are two drains up front for them.

I recently changed out my tranny/transfer/differential oil, and it shifts so much smoother now. I went with Walmart brand 80w-90 gear oil.

[SuperRA]

I could be wrong, but I think Redline MTL and MT-90 are formulated for use specifically in manual transmissions.

[eage8]

I know because I have 2 differentials in my Subaru's transmission they recommended I use the 75w90NS. possibly because ones a viscous LSD? I'm not sure... I would email Redline about it, they've been helpful to me in the past.

I use redline in all my cars and it seems to work really well. I think my subaru's transmission was too far gone for it to help the crunches though... One alternative is using royal purple or mobil1. You can find both at advance autoparts.

[rdyzz]

i've had good sucess using 1 quart of ams oil 75w-90 mixed with the rest being gm syncromesh. this seems to be even more agressive then the redline mt-90. also you can always order redline mt-90 from jegs or online sources. locally gm syncromesh works like a charm. gear oil's are just a bandaid to worn syncros.

[eage8]

the cheapest I've found redline is from ogracing.com. They're also really close to me so I get it the next day

[Flashmn]

gear oil's are just a bandaid to worn syncros

Some gear oils kill synchros, they cause yellow metal corrosion if they have active sulphur compunds. Its gonna destroy the box. However if toyota says to use GL-5, then it would be ok to use in that particular box and there might be some other requirements of that GL-5 oil in the owners manual too and some GL-5's are "yellow metal safe"

i've had good sucess using 1 quart of ams oil 75w-90 mixed with the rest being gm syncromesh

You should never mix two different oils, the additives they have might not be compatible and you might end up with a bucket load of shit.
MT-90 is quite stiff for a toyota box, I have 3 bottles waiting to be put into mine, winter is gonna suck with a cold gearbox MTL would be closer to factory specs. As for GM synchromesh, thats designed for GM gearboxes and the additives included are designed for them. MTL and MT-90 are both GL-4 oils.

[rdyzz]

i mixed it because if you've ever seen gm syncromesh that stuff is about as thin as motor oil when comparing it to gear lube.

[Flashmn]

Even more so it might turn out bad, if the fluids are actually very different, worse case scenario is they wouldnt even mix properly. Just because its thin doesnt mean its bad.

For example honda uses motoroil in the gearbox, Mercedes uses either motoroil or ATF in their manual gearbox, I cant remember which it was. VW has their own VS200 formulated gear oil, etc etc etc etc. Its the wrong stuff for the application.

Fords often use their own stuff in everything, using other than their own Formula F engine oil in a 16V engine will kill the lifters. Theres a reason things differ, its mechanical differences that need to operate with the correct fluids or something will go bad.

AE92 gearboxes are relatively old, so they're not particularly picky, but old gearboxes have mileage which means they have wear, so to keep the gearbox healthy for years to come would even more-so need the right fluids.

[eage8]

Originally Posted by rdyzz

i mixed it because if you've ever seen gm syncromesh that stuff is about as thin as motor oil when comparing it to gear lube.

why don't you just use all amsoil? it's supposed to be really good.