Manual Transmission Fluid GL-4 or GL-5 ??

I think I'm going to go with this - it's CRC and I've used a lot of their products over the years. You're happy with it - how many changes did you do with it ?

 

I have 121,000 on it and changed it at around 60K. I tried Redline in my 98 and really didn’t see any improvement in shifting. I went back to the CRC in it when I had it.

 

1st and 2nd gen Miatas all had off the shelf truck transmissions, all bronze syncros, all best with GL4

As you can imagine, most autocrossers (a LOT of Miatas) maintained their vehicles well, and tried a bit of everything in the gearbox, trying to find that extra snic snic shift. And straight up GL4 was tough to find.

I had OE fluid then Royal Purple. My next move was going to the Ford elixer, because it had tested exceptionally well with a tribologist I knew from Miata.net and several other members who were impressed with the improvement it offered.

Remember, an autox vehicle in daily use is likely pushed harder than a daily Tacoma, and light nimble cars driven by seasoned folks tend to notice even the little things. (think Ken Miles in Ford vs Ferrari)

I know that's a lot of typing. But if my Tacoma was manual, and it shifted well enough, I'd use an OTC synthetic in the right SAE wt and GL rating. If I was looking to improve feel, and the shifter bushings and such were all in good shape, I'd spring for the Ford stuff.

Either way, going to syn over dino, I'd extend the OCIs 50% at a minimum.

 

from Bob the Oil Guy - looks like he say GL-5 is OK

Here is the basic about the difference in gl-4 vers gl-5 API GL-4 Denotes Lubricants intended for axles with spiral bevel gears operating under moderate to sever conditions of speed and load or axles with hypoid gears operating under moderate speeds and loads. These oils MAY be used in selected manual transmissions and trans-axle applications where API MT-1 lubricants are unsuitable. API GL-5 Denotes lubricants intended for gears, particularly hypoid gears, in axles operating under various combinations of high speed shock loads and low speed, high torque conditions. Lubricants qualified under MIL-L-2105D satisfy the requirements of the API GL-5 specifications. API MT-1 Denotes lubricants intended for non synchronized manual transmissions used in buses and heavy duty trucks. Lubricants meeting the requirements of API MT-1 provide protection against the combination of thermal degradation, component wear and oil seal deterioration. API MT-1 does not address the performance requirements of synchronized transmissions and trans-axles in passenger car and heavy duty applications. Discontinued Api not in current use. API GL-2 API GL-3 API GL-6 Anyway, this is just a touch of what the difference is between some of the classifications. The big difference is EP additives and the type of gears they are designed for. BOTH GL-4 and GL-5 address the copper issue and Both are compatible in this area. There's more to this on specs and such but as I was researching this, I kept looking at the schaeffers 267 gear oil tech data and noticed that they show to cover the MT-1 specs, the SAE J2360 spec, the MIL 2105 spec all of which makes a better oil than standard gl-4. As pointed out above, its the design for specific load and gear types that make it different and that's based on the fact there is a difference in ep additives between the two. I hope this helps clear up the mis information about corrosion to copper and such.

 

"I kept looking at the schaeffers 267 gear oil tech data and noticed that they show to cover the MT-1 specs, the SAE J2360 spec, the MIL 2105 spec all of which makes a better oil than standard gl-4."

"Better" -- Folks always get hung up on better. The correct oil is what is important.

Although the Schaeffers product also covers the MT-1 specification this is not an asset in the Tacoma as none of the MT-1 service conditions (intended for non synchronized manual transmissions) are found in the Tacoma.

The 3ed gen owners manual specifically calls out a GL-4 oil for the manual transmission.
You haven't provided the year of your truck and state that your owners manual calls out GL-4/GL-5 oil so I will assume that it is an earlier model.

Something to be aware of is that sometimes manufacturers change specifications both as new products come out and also as they accumulate data. The fact that the newer model specifically calls for a GL-4 oil suggests that Toyota has decided that the GL-5 product wasn't offering the performance the engineers desired.

"The big difference is EP additives and the type of gears they are designed for."

Yes, exactly -- designed for being the key.

Most of the GL-4/GL-5 information provided above refers to axle applications.

The hypoid gears in an axle are subject to both a meshing and twisting motion - conditions not found in a transmission application. The modern EP additives in a GL-5 oil are very tenacious in staying on the gears when subject to this twisting motion.

My understanding of the use of a GL-5 product in a synchronized manual transmissions is as follows:
The very tenacious additives actually have "too good" of a bond on the softer metals of the synchronizers and rather than allow themselves to be removed they actually rip out microscopic bits of metal when shifting.

The rate of wear probably depends on hundreds of variables better studied in a laboratory than the driveway but there is enough evidence to establish it as something that one wants to avoid.

This is easily achieved by using any oil carrying only the GL-4 specification, a product marketed as GL-4/GL-5 is not suitable as to meet the GL-5 specification it will have the more tenacious additive package. I personally chose to avoid products that claimed that their GL-5 additive was "acceptable" for GL-4 manual applications as the correct specification oil was easily obtainable.

I purchased the Motorcraft XT-M5-QS product, it satisfies the Toyota specifications and seemed to make the shifting slicker versus the factory fill. Rock Auto had the best price.

https://www.rockauto.com/en/parts/motorcraft,XTM5QS,transmission+fluid,13630

 

"You haven't provided the year of your truck and state that your owners manual calls out GL-4/GL-5 oil so I will assume that it is an earlier model." 2008 Tacoma 2.7 Manual Transmission - owners manual does state GL-4/GL-5 . Profile on left of post use to say 2008 Tacoma but no longer does and I don't know how to edit it - if you or anyone does I'd be glad to add 2008 Tacoma - Thanks.

 

1) Click on "You" in the upper right of each page
2) Click on "Personal Details"
3) Scroll down to "Vehicle One-Line Description"
4) Edit accordingly
5) Click "Save Changes at the bottom of the page

 

Ok - Done - It worked - Thanks.

 

I think his question was in reference to the Toyota fluids being in the old style metal topped flat cans. These, traditionally used a push in spout and are not going to work for direct dispensing since you can't "pour" the fluid into a manual transmission on a Tacoma. We know it has to be pumped or squeezed. How do you do it from one of those cans?

 

I use the pump I referenced. Like this, or you can buy an empty quart container and pour the Toyota fluid into it and use the pump I referenced on that. Either way it works.

 

What do you have clamped to your exhaust in the picture and why ? Thanks