irv

I know that this is a topic that looks like it's been discussed pretty extensively online. Although market options of gear oils have changed a bit since many of the threads I've looked at.

From my searching it definitely looks like Redline GL4 MT-90 is the most preferred and recommended gear oil for our manual transmissions.

I understand that GL4 is recommended over GL5. Seems like GL4 is said to be better for internal brass components.

Other than Redline, what may be a second best option that isn't quite as expensive? Anyone used this Sta Lube oil?
It is a GL4 oil but is 85w90 rather than the recommended 75w90 or 80w90 that our transmissions call for.

fdp101452

I know nothing about Stalube and its 30 bucks cheaper and I suppose it would work ok, but how often do you have to buy trans oil? When I change mine I'm going with Red Line because I think its worth it and my pickup is worth it. I'm not bashing you, its your pickup and your money but I for one wont cheap out on this sort of thing.

flg8r22

iTrader: (1)

I've run Amsoil products in everything I own since the late 90's

irv

I have negative $35 in my checking account. haha Everyone's situation is different. 32 years old, self employed and sometimes I have money on hand and sometimes not. Transmission died in my 86 4x4 daily driver. Something let go and it catastrophically failed. Metal chunks came out when I drained it. So I'm swapping in a used w56 and have to fill it up with oil. The truck is in great shape for it's age and it's all stock and is my reliable daily work truck. It's not a rock crawler or off roader or souped up hot rod. Just need it to reliably hold up. So I don't necessarily need the best of the best parts or oils. I just need an oil that is acceptable as a standard option and that doesn't have additives that are harmful. Maybe it won't be synthetic or have the best marketing or statements about how fantastic it is but that's ok if it works.

irv

I assume this product? http://www.amsoil.com/shop/by-produc...r-lube-75w-90/

fdp101452

I understand, I'm self employed, have calluses that are more than 32years old and had -46.00 in my check account this morning. Far be it from me to throw rocks at anyone. I live in a two story glass house. A man does what he has to do.

87yo_ta

I believe Sta-Lube is made by CRC which has been around forever. I have owned my '87 22R 4WD Pickup for 30 years, use it as a daily driver (300k miles) and have used Mobil 1 & Amsoil synthetics as well as various other brands of non-synthetic oil over the years. Still shifts great, so in my opinion any decent quality GL4 oil will work. I change a non-synthetic oil more often but I don't necessarily worry about it. BTW, the Mobil 1 is GL5 and I never had a syncro issue. I am currently using Redline MT90. Great stuff but a tad expensive.

RJR

Modern GL-5 gear oils won't damage the brass synchros - that was apparently a problem years ago but oil manufacturers have fixed that from what I've read. However, GL-5 is still slicker than GL-4, to accomodate the sliding gear meshing in the hypoid gears of the differentials. That makes GL-5 not work as well in synchronized transmissions, because it causes the synchro clutches to slip instead of spinning up the gears during a shift.

Toyota says GL-5 is OK in your tranny, but most people say shifting is better with GL-4. I just had my chain-drive tcase apart and I refilled with the GL-5 I had on hand. I notice now that "on-the-fly" shifting from 2H to 4H, which depends on a synchronizer to spool up the front drive shaft, no longer seems to work. I'm going to order a couple of quarts of GL-4 and see if that makes a difference.

spddm0n

Interesting discussion! I've not read anywhere that GL-5 has been reformulated to NOT damage soft yellow metals, that would be news to me. I would like to see some proof/ownership that it actually DID cause damage and the new formulas that won't do this. Call me skeptical, but I find these big companies willing to say/do anything to keep their shareholders happy, above their customers (usually end is cost cutting measures). I had a rather difficult discussion with Lucas at one point, as they have now printed their labels to say GL-4/GL-5 compatible. They would NOT give me a technical answer to this compatibility (reformulated).

I just went through this whole charade with my Nissan Xterras (I rebuild them for customers). Same older transmission with soft yellow metals. I searched and searched and searched, looking for a lower cost alternative to manufacturer OEM Gl-4 oils and Redline/Royal Purple (yada yada). The result was also Amsoil. I have a commercial account with Napa and they stock in now. I think I'm paying $13.75/quart. Ugh. That's still twice and high as I would like to pay, especially in volume (almost $100 change for every Xterra 5 speed oil change).

I would be more concerned about the weight of the 85w90 than I would shifting properties of a "reformulated GL-5".

Anyone else know of a middle of the road 75W-90 GL-4?

millball

I am able to buy a semi-syn 75w-90 GL-4 gear oil from Colorado Petroleum that they market as 'Rugged Euro 75w-90'. It is a great product, and all my syncro trannies like it.

I have a friend who is able to get it for me at employee pricing, and I'm ashamed to tell how reasonable the price is for 5 gallon pails.

I also buy their 'Silver State' brand GL-5 full syn gear oils for diff fills.

Even at list, it is very affordable. I know they have distributors in Colorado and here in Arizona, where I am. Google Colorado petroleum and you will find their website.

spddm0n

Wow! Sweet! Thanks for the reference. I'll be just down the street from the in Denver tomorrow.

Ill be be curious to see how their prices are.

Nice!

millball

Let us know how you do. As you say, reasonably priced GL-4 oils are not so easy to find.

RJR

Here's a link to an interesting paper about GL-4 vs GL-5. I supports what I wrote about synchro damage vs. smooth operation.
http://www.widman.biz/uploads/Transaxle_oil.pdf

spddm0n

I've read through that document on a couple of occasions. Can you call out the area of the document supporting that GL-5's are backward compatible and won't damage soft yellow metals?

Also, I just got off the phone with a petroleum engineer at Colorado Petroleum. He indicated this was not accurate. The "amount" of the additives in Gl-5 WILL damage the soft yellow metals, over time. The question is "how long?".

I won't get into the conversation we had on why manufactures (both petroleum and automobile manufactureers) are suggesting GL-5 as "meets or exceeds" standards of GL-4, but the additives in GL-5 WILL slowly damage your soft metals over an extended use of the oil.

FWIW - They can sell me a 5 gallon pale of GL-4 gear oil (35 lbs) for $2.92/lb (about $100 for 5 gallons, or $20/gallon, or $5/quart). If there are any local Colorado people who need some, by the quart, I'm happy to pass it on at $5/quart. Of course, this might be counter-intuitive if you have to drive very far to get to me. It looks the average 4WD with manual transmission takes about 5 quarts between the transmission and the transfer case. I build a lot of 1st Gen Nissan Xterras and those call for almost 6 quarts in the transmission alone, so I can go through it pretty fast.

Also, do you guys match the fluid in the transfer case with the fluid in the transmission? I noticed the FSM suggests the GL4 (or GL-5) for the transfer case on vehicles with manual transmissions, and the Dexron II ATF for the transfer cases on vehicles with the automatic transmission.

RJR

So I think I'm guilty of too casual reading. The second paragraph under the "History" section indeed indicates that "Somewhere around 25 years ago a deactivated or buffered sulfur was developed that would react with the phosphorous to create the protective/sacrificial layer in the conditions created in the gear boxes(temperature and pressure) without being corrosive to the brass, copper, ec." This is the part that lead me to believe modern GL-5 is no longer harmful to the brass synchros.

However, later in the article he says "But when one or more of the surfaces is brass or another soft metal, the sacrificial coating is stronger than the base metal, and instead of just peeling off, it takes with it a few microns of brass that it is bound to." So, while no longer "corrosive", the extra sulfer in GL-5 still appears to be somewhat damaging.

It is interesting that Toyota specifies either GL-4 or GL-5 as being suitable for their manual transmissions. Can't go wrong sticking with GL-4, though.

Your other point about matching tcase fluid to transmission fluid is interesting. In the manual transmission setups, there is a seal between the two units, so tcase fluid should normally never mix with the tranny fluid, so they could be different. In the auto transmission setup, the two gear boxes share fluid, so the tcase has to live with ATF. Interesting, all of the actual gears and bearings in the auto tcase are identical to those in the manual tcase, so obviously the tcase is not really all that fussy about what kind of lubricating fluid is used. The A/T tcase does not have the lo-high synchronizer that is in the M/T tcase.

spddm0n

Interesting Ron!

I have often wondered if the transfer fluid is mixing with the transmission fluid. I've never actually pulled them apart to look! This is my first auto transmission in a Toyota truck. The Xterra's I'm building call for either ATF or GL-4 in the transfer case, regardless of the manual or auto transmission. I did call a 4X4 earlier in the year and ask about the two sharing fluid, and he indicated they do not.

Also...interesting that the guts are the same in the transfer case (manual or auto). Looks like either fluid can work. I'll continue to match fluids. Now that I found a cheaper source of GL-4, it helps tolerate the cost of using the otherwise expensive gear oil in the transfer cases.

Charchee

If you just bought a new crate Toyota transmission for your rig then this discussion may be valid but if we are talking about a five speed with 150k miles or more on it then gear oil is going to be gear oil. Find you a good quality GL4 or GL5 80W-90 and change it every 30K or so. I do like the Amsoil products if you are real particular. I worked in a Caterpillar oil lab for years and after staring at the spectrometer analysis of all different kinds of oils I realized that after components were well broken in, the wear metal readings were no different between the high end oils and low end oils so long as they were changed regularly. You could see some difference in newer components but they were indistinguishable after they were broken in.

I say, buy a gallon of moderately priced, readily available gear oil and put it in there. If you honestly feel a difference that you don't like, drain it and fill it with whatever your research tells you to put in there. That's just the two cents of a guy who studied this stuff through an electron microscope without a dog in the fight.

millball

Fact is that the older and higher mileage a tranny is, the more likely it is that the GL-4 oil will give better results than the GL-5.

A tight new trannys syncros will be at their best, and are likely to work well, even with the more slippery GL-5 spec oils.

An older tranny with many years and miles on it is bound to have some syncro wear and degradation, and it will certainly function better when less slick GL-4 spec oils are used.

Charchee

Millball is one of the folks on here who's advice I will follow no matter what he says. Go with whatever he says, as will I. Insert tipping hat image.

millball

Charchee, you are much too kind.

I defer to your experience with oil analysis, and I agree about there being little or no difference in metallic wear products regardless of different type oil usage in components that have seen long service...

It is only the enhanced slickness of GL-5 oils that is the bugaboo of well worn syncro trannys.