3rd Gen Differential and Manual Transmission (6MT) Fluid Change

I paid the dealership to do the TCase because I figured it will cost about the same! When I looked at the report they used

$29 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90 in there!

 

This seems to be a standard experience. Many or most, perhaps not all, Toyota dealer service center have no knowledge of this magical LF fluid. Mine had never heard of it, and they probably service 5 Tacomas a day.

 

Yeah, it specifically calls for straight 75W GL4 which has less sulfur than the 75W90 (75W85 actually) GL5 gear oil in the diffs.

I’d make them credit you the cost to change the Tcase fluid and get a bottle of Ravenol and redo it yourself. It’s like $16 a bottle

 

The owners manual doesn't specify if GL-4 or GL-5?

 

I don’t have the manual with me, but I thought all straight 75W were GL4 specifically for Tcases and Manual Trans.

If you have the owners manual info let me know

 

Redline Oil make an SAE 70w/75w GL-4 and a 75w85 GL-5 that also subs for 75w. Not sure which would be appropriate as the owners manual doesn't specify GL-4 or GL-5.

 

The manual only gives us the mysterious “LF” 75W label for the T-case. No Gl rating.

 

I see, thanks for the info. My only concern would be that GL5 for the diffs has more sulfur which isn’t good for manual trans syncros. Wondering if this would apply to the Tcase, as well?

 

It is just a simple fact that the dealer will never change any fluid other than the engine oil in my Taco and only for the length of ToyotaCare. I feel that Ravenol fills the bill as an option to the Toyota brand. Myself, I am not risking the t case by using gear oil spec'ed for the diffs.

 

That’s what I did too in the Tcase, I never actually go to the dealer. (But, may have to with the AC blower fan recall)

 

There is one bronze synchro ring in a T-case, which sees 1,000,000 times less use than the synchro rings in a manual transmission. The issue of sulphur eroding the surface of yellow-metal synchronizer rings is really only an issue when they are engaged or disengaged often, as the sulphur work-hardens the surface. Unless you are going back and forth between 4wd and 2wd constantly, it is likely not an issue.

My best guess: this LF fluid stands for “low friction” and is used for fuel economy. In a Tacoma transfer case, the chain runs all the time due to the lack of locking hubs. I imagine a small amount of power is absorbed running the chain through the oil bath so they want as little fluid resistance as possible, hence the light oil. Same reason they are using 0W20 in the engine. It’s all about saving fractional amounts of fuel.

 

Thanks, that’s what I figured for EPA CAFE standards

 

On behalf of 3rd gen MT owners, thank you for putting the time for the excellent write up that will benefit us all.

 

Here is a video that may set people’s fears aside if they think their dealer put GL-5 75W90 in their “LF-75W” T-case, by mistake. In this case the video subject is 4-speed manual transmissions, but the same factors apply.

The talk about gear oil starts at the 11 minute mark or so. Pay particular attention in regards to the concepts of “windage” of the oil and how that robs horsepower (think of the amount of sloshing in your T-case). Consider Toyota’s goal of a very fuel efficient Tacoma, as opposed to the best possible lubricant for the T-case.

Also......this guy’s Youtube channel is great. I don’t own a 4-speed muscle car, but I’m a fan of people who know how to do practical things. This fella certainly is a guy who knows his shit.

https://m.youtube.com/watch?v=Z7NpsMZ9pBQ

 

It isn't so much that gear lube is good or bad. It's that there is an oil that meets the spec for a very reasonable price. From that standpoint, it cramps my brain (easy to do) to use anything else.

 

For sure, I realize that, but there’s a few guys running around with 75W90 in their T-cases after a visit to the dealer. If that’s a worry for some, I thought the video might help alleviate those fears.

 

Gear oil for differentials should not be used in synchro transmissions since the gear oil made for limited slip diffs is to "slippery" for transmissions and trans cases according to Redline.

 

I did owned a "muscle car" in the 70s a Chevy II with a 327/Crower cam, sponsored by Crower (Super Stock class) and always used Valvoline in trans and differential. Never a problem, but it was all conventional oil back then. I never lost a Muncie 4-spd, even power shifting drag racing on the street and Carlsbad Raceway, San Diego (now long gone). I've watched this guys videos, and you'll notice that he said that the engineering of the new GL-4 and GL-5 synthetics is way better than it was decades ago. So, I'll stick with GL-5 in my diffs, and GL-4 in my trans and transfer case. I use Redline, but have used Valvoline in past Tacomas. That's my $.02.

 

Almost that time again...



Amsoil sells their severe gear fluid in these "easy pack" containers now (which are much bigger than I'd expect for a quart of fluid). It's essentially a bag with a nozzle/tip. They cost the same as the regular quart containers and I'm hoping they work decently well (or it's going to be a pain using that shitty bottle pump lid).



I should have my driveway time Saturday booked out to do this and my regular u-joint greasing and seasonal fluid film. Typically I wouldn't fluid film until early December here, but I figure since I'm already going to be under the truck, why not?

Blackstone will receive the 3 samples per usual, but this time it will be measuring 20k miles on Amsoil fluids rather than stock.

OA

 

Nice! I like those lube bags. IMO, it might be easier to squeeze in the first three for the rear and the first one for the front, then get the pump out to top off? The front fill hole might be a bit tough, but then, you might be able to get the flex hose from the pump to stay on the ridge of lube spout?

I'm looking forward to the UOA results, esp after the questionable stuff for the OEM MT fluid.