Gear oil question

The Transfer case has synchronizers. Look here: https://parts.lakelandtoyota.com/sh...key_driveLine=6782&searchString=transfer case

 

Your skepticism is reasonable. You should apply that same skepticism to your owners manual. Off the top of my head, I remember some resource (either my chiltons manual or owners manual probably) saying that the tranny takes gl4 OR gl5 fluid. GL5 supposedly eats brass synchros. Search and you'll find a lot of info on this topic. Why not play it safe and use gl4? Redline is a lot cheaper than a transmission. My chiltons also says to add like 6.2(?) quarts for an oil change, and torque the leaf springs to 37ft/lbs (should be 73), so those manuals should be taken with a grain of salt.

 

Interesting, I can't remember why at this time, but I remember concluding that plain gl5 gear oil was fine for the transfer case last time I researched it. I wonder if they're brass? I think that is the problem with the gl5

 

The problems regarding the lubrication sensitivity of this transmission are well documented on this site, and every other Tacoma site. Try doing a search. GL5 lubricants are designed for use in Hypoid gears because of the extreme pressures. They are far too slick for use in any manual gear box. The sychros are a wear part, sort of like a clutch. They require a certain amount of grip to spin the gears up to speed. This was not such a problem before the advent of super slick oils. Now these lubricants have to be specially formulated to provide the gear protection needed while allowing the synchros to do their work. That is the functional problem. GL5s contain sulfur bearing compounds that produce mildly acidic conditions in the oil. It's a not a problem for steel components or seals, but it does attack the brass in the synchros.

Back when I first bought my Tacoma, and noticed the shifting issues, I personally tried the following oils: dino, Amsoil, Lucas, Mobil 1, Redline, and one other that I can't recall. The Redline was by far the best, and the Mobile 1 was the worst.

 

I always used a GL5 in the transfer case and manual transmission(when I had one) and never had any issues, also I think the manual states using a GL 4 or GL 5 in them is OK

 

Three quarts is the exact amount to fill the transfer case and the tranny, so using one oil makes sense.

The very characteristics that make GL5 an excellent hypoid oil (differentials), is what makes them terrible for transmissions. Toyota is not the authority on anything regarding manual transmissions. The Tacoma 6 speed and clutch is a study in mechanical dysfunction. Why would anyone trust their advise on lubrication?

 

he he he he

 

God damn it!

I was planning on grabbing 6 Mobil1 Synthetic Gear Lubricant LS 75W-90 (1 qt.)
and a ToughOne Engine Fluid Oil Pump

To swap out my front dif, transfer case and rear diff oil based on this thread https://www.tacomaworld.com/threads/front-diff-and-transfer-case-oil-change-howto.147631/

Are you saying now that this is not what I should be using?

 

I use Mobil-1 5W-40 in the 2.7L 4x4 Tacoma's engine & Mobil-1

$28 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 in front differential & transfer. Why? Texas heat & very rural environment. Just like most of you, MT-90 (GL-4) in the transmission. Amsoil 75W-110 (GL-5) in the rear differential. Again, 100*F+ temperatures, dust & dirt roads and trails. My choices might not be best for the vast majority of you who live in urban areas.

 

Read your owners manual. Mine clearly states GL4 or 5 in transfer case. GL5 for Dif(s). The finer point being discussed here is what to do with "Manual Transmissions". My manual says GL4 (manual trans).

I have Mobil 1 in my difs & transfer case. WS in my auto transmission.

 

The owner's manual for my 2008 does indeed say GL4 or GL5 are fine for the transmission and transfer case. I use GL4, Redline MT90 personally, for the many times documented reasons here and on the Interwebs (GL4 is less harmful to yellow metals).

You want to use GL5 hypoid gear oil definitely in the diffs and the transfer is indifferent, it's got neither hypoid gears nor yellow metal.

FWIW, in my old truck with a gear-driven transfer case I did use hypoid gear oil instead of MT90. My thinking was even though you shouldn't really need EP for straight cut (or rather more precisely helical cut) gears, I couldn't see how it would hurt and might be better. I dunno.

Last time I used the same stuff as the diffs because I only had 2 quarts of MT90 on hand but when I'm buying for a complete oil-ectomny doing 3 of one type (transmission/t-case) and 5 of the other works, too. Either way you need 8 quarts and will be left with a little bit of GL5 at the end.

Well, that is if you're better than I and haven't spilled some, in which case the ~0.5 quarts you should have in theory is slowly lubricating the wheels on your creeper and leaving tracks all over the floor.

 

OK....so when I read my owners manual it stated that for my 2006 transmission it was ok to use GL4 or GL5 for the manual transmission, and for the transfer case and for both differentials. Mobil 1 and super tech is what was available, so I chose Mobil 1 over the Wal-Mart super tech brand.

I'm not sure why it was asked, but I have an android device.

 

Are you asking why GL4 vs GL5? That's a searchable moment. But I will say that GL5 in 2017 is in fact somewhat safer than it was when first specified. That's because the sulphur is often (or sometimes perhaps) buffered to be less reactive with copper/brass/bronze. But it's still safer yet to use GL4 because there's no API directive that GL5 must use buffering and therefore no guarantees.

Regards Mobil1 vs Super Tech. I dunno, I'd probably opt for Mobil too, but I'm snooty.

 

Yes....Im asking why the GL4 vs GL5. If the manual says both are ok for it than I would think it would be fine. I'm going to do a search on the rest of the site for this issue since folks are saying its well documented.

 

I don't know why Toyota changed the spec to allow GL5 in the their manual transmissions. It used to specifically say GL4, so maybe they found it doesn't wear them exceptionally fast or they have changed alloys or coatings to reduce the synchros susceptibility. Or perhaps they figure since throwout bearing wears the nose so fast that you'll be replacing the transmission before the synchros are gone anyway.

One thing is don't worry, putting GL5 in there isn't going to ruin it right away in any case. I ran GL5 in my old W56 for 30K miles before I understood the difference and that was a GL4 only specification. That transmission had 100K when I did that and went another 150K on MT90 and is still going AFAIK. So I wouldn't get crazy over it.

Another thing, I personally don't like the way hypoid lube shifts, I was grinding it more. But that's somewhat individual, how fast you shift, your clutch timing, etc. How different specs and weights work on the synchros impacts this.

 

I would suggest that you get the GL-5 out of the transmission. I tried that route on my 5 speed before I knew better and the transmission started shifting terrible esp wen cold and also began shedding yellow metals like crazy. Someone with a '14 or '15 please chime in on whether the owners manual is now stating the dual GL-4/GL-5 or only GL-4 for the 5 speed. I can tell you that on the 6 speed Toy used to dual spec it but quietly dropped the dual designation on later models and it is GL-4 only, same transmission as the early ones.

 

What about the transfer case?

 

Features and Potential Benefits
Mobil 1 Syn Gear Lube LS

$28 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 combines wax-free synthesized hydrocarbon base oils and a specially designed extreme-pressure, limited-slip, sulfur-phosphorous additive system to help provide a significantly higher level of performance in rear axles and differentials versus conventional fluids. Great film strength at higher operating temperatures, reduced fluid friction and low-temperature application down to -50ºC helps to provide significant advantages versus conventional mineral oil formulations. It helps to reduce wear and spalling under the high speed, high torque and high horsepower conditions in competitive racing and high performance automobiles. This unique, high technology final drive gear lubricant has demonstrated outstanding performance including fuel economy, extended drain, long-term friction retention, low-temperature capability and improved differential/axle durability and cleanliness. Key features and potential benefits include:

Features Advantages and Potential Benefits
Exceptional thermal stability and resistance to high temperature oxidation Helps to extend gear and bearing life due to minimal deposits
Long seal life
Potential extended oil drain/service intervals
Outstanding protection against low speed/high torque wear and against high speed scoring Capability to handle some of the severest driving conditions while delivering smooth efficient and reliable performance
Exceptional shear stability Helps to retain viscosity and film strength under severe operating conditions to prevent wear
Excellent rust, staining and corrosion protection of copper and its alloys Helps to reduce wear
Long component life
Enhanced frictional properties Improved fuel economy and reduced operating costs
Outstanding low temperature fluidity versus mineral oils Helps to reduce wear at start up and ease of start up even in arctic conditions
Good resistance to foaming Helps to maintain film strength for reliable lubrication
Compatible with typical automotive seals and gaskets Helps to minimize leakage and reduce contamination
Excellent limited-slip performance Helps to reduce chatter and improve traction



Ok...so the above was taken from the Mobil 1 website about the oil I used. It seems that they have addressed the issue per the line I bolded and underlined?

 

The transfer case is the most tolerant component in the drivetrain, anything that matches the viscosity will be fine.

Perhaps. GL5 (and GL4 for that matter) doesn't have anything in the specification that determine suitability for transmissions. The individual formulation ultimately determines if it's going to work. Some do claim to be safe for yellow metals.

All anyone is saying here is that (1) GL5 is usually not good and (b) Redline MT90 is made to work well in manuals. Most real experience confirm those things, take it for what it's worth.

 

What anybody chooses to use is of no concern to me. Just sharing my choices and why.

While on the subject, I will mention one other thing. I see ideas about what to use in the transfer case all over the place. I have seen people using heavy gear oil in them to make them quieter. I don't know how many people realize that the transfer case is not splash lubricated. It has an internal oil pump with a very fine screen on the pickup. Heavy oils will not pass the screen efficiently, and the transfer case will be starved for oil. This can cause premature wear and failure. I would definitely stick with a transmission oil.