Differential Gear Lube Dilemma - Mystik JT-7

[spooltime]

In September I had an awful time at the indie near me that is well known for work on Toyota’s and 100’s, but now appears likely they have little to no experience on a 200. I can get into the whole issue about a failure to bleed my KDSS valves necessitating me to correct a lean myself, but that will detract from present issue.

After a really bad experience, I vowed not to go back, so this weekend I took my 13’ with 145,000 miles to local Toyota service department for oil change and coolant exchange. They were very concerned about the color of my differential fluid, which they said appeared red, compared to the clear / yellow / amber of the LT 75W-85 GL-5 which is what they use a recommend.

I just got off the phone with the indie, and they indicate they use non-synthetic Mystik JT-7. Looking at Mystik’s website, they have two non-synthetic Weights 80w-90 and 85w-140. I have to assume they used the 80w, and I guess I should call back and confirm. They seemed confident, indicating they have used the same diff lube for over 50 years.

What are your thoughts? Should I leave this Mystik product in? Redo it?

I realize i should have verified this first, but I guess I was more concerned about verifying they used Toyota WS transmission fluid for the tenant fluid exchange and that they understood the KDSS system and I forgot to ask about specific diff lube.

What should I do? So aggravating that I went to great lengths to find an indie, do almost $2000 worth of preventive maintenance and now have a non/confident feeling in my gut.

 

[04UZJ100]

DIY stuff like this. It’s literally foolproof.

I’d change out for piece of mind.

DIY....

 

[linuxgod]

Aftermarket gears like Nitro recommend 80w140 or something similarly heavy, as compared to the Toyota 75W85 stuff. If you're not in an incredibly cold climate where low temp performance is key then honestly it's probably fine, and in fact if you're towing or putting the gears under heavy load it might even be preferable. I'd likely run it for a while and then swap it later, but I also tow and end up changing my diff and TC fluid every 30k.

That said I would be irritated that the other shop used something outside of the mfr spec without advising you, and you're well within your rights to demand they refund the cost since you're going to do it over.

 

[ga12r1]

You will be fine. I wouldn't worry about it. Just change to what you prefer in 30k miles.

 

[bloc]

As long as it's GL-5 rated, which pretty much any gear oil should be, I'd have no problem running it for 30k, then dump it and put in whatever you want.

 

[SWUtah]

Same reason I haven’t had anybody change my transfer case fluid, I only have 49,000 miles on my truck but the special fluid that comes from the factory not even Toyota or Lexus uses that fluid when they replace because it’s too expensive.

 

[JS22STL]

Fluid for the 2 Diffs and trans case are around $300. It’s not cheap going Lexus/Toyota branded lube. Lots of threads on here for other options If you go that route.

 

[linuxgod]

Same reason I haven’t had anybody change my transfer case fluid, I only have 49,000 miles on my truck but the special fluid that comes from the factory not even Toyota or Lexus uses that fluid when they replace because it’s too expensive.

If you're not using 4Lo or towing then I agree, you can just follow the maintenance schedule in the manual. I don't recall offhand what it says, maybe "check and replace if necessary"? If so that could be 150k+

 

[airdzi]

My honest recommendation is to change the gear oil, stick to original gear lube as far as 60k but if your differential lock light comes up on the dash when cold and disappears on warm start (Low level, severe use, small seal leak, stuck breather) it is time to change all of the gear fluids, despite dif lock being indicative of transfer case only (center diff).

Ravenol 75W for transfer case (2 quarts) and Ravenol 75W-85 for diffs (7 quarts). 9 quarts total set me back $145 from Blauparts. Ravenol fluids are fully synthetic, Made in Germany. Likely superior to OEM so no need to overpay for Toyota branded gear oils. I went as far as Toyota WS, brake fluid and coolant but for gear oils went Ravenol with great results.

Made choice of 75W for transfer despite OM calling for 75W-90 (for some model years). Unless you are in the desert 90 viscosity is not required and newer models US specs call for 75W with the identical transfer. That change alone cures the diff light showing up on the dash during cold starts. No matter which way you go you would be fine as dif light is rarely a problem with fresh fluid. But once you start getting it - it does not trigger engine light but it disables your cruise control so it is annoying.

Be careful when draining front diff, plug is huge and it is a gusher, have a big drain pan ready.

 

[bloc]

There is a change around 2010 in the center diff of the transfer case. Suspicion that they added a syncro made of some yellow metal and that means GL-5 fluids (most 75w-90) won’t play nicely.

 

[airdzi]

There is a change around 2010 in the center diff of the transfer case. Suspicion that they added a syncro made of some yellow metal and that means GL-5 fluids (most 75w-90) won’t play nicely.

Thanks, very possible, wonder if they changed the part number.

 

[bloc]

Thanks, very possible, wonder if they changed the part number.

They did. That is the easy part, but none of us had torn one down. Bjowett is pretty much the guru on this.

 

[airdzi]

They did. That is the easy part, but none of us had torn one down. Bjowett is pretty much the guru on this.

Very interesting, you would think how sensitive can gears be about gear lube, well, even that is down to the science and it sure knows, because the day I changed mine the diff lock light was no show.

 

[spooltime]

Thanks everyone. Excellent information. You have all really put me more at ease. I’ll change it after 30k miles, which is 24k from now.

 

[rlynch356]

I just did mine and used the Toyota GL-5 75W transfer case lube they specified 08885-81080, it's $60/liter, my thoughts were that the interval change is 30k so its cheap insurance to use the OEM stuff here.

 

[Cruisin911]

I just did mine and used the Toyota GL-5 75W transfer case lube they specified 08885-81080, it's $60/liter, my thoughts were that the interval change is 30k so its cheap insurance to use the OEM stuff here.

Same here. May be unrelated but I was fighting a flashing diff lock light during the winter months when on Mobil 1 75W-90. Went with the toyota crazy expensive stuff and I haven't had an issue since. This may be anecdotal given how much I want to believe I fixed it through justifying the cost of that lube....

 

[airdzi]

Ravenol lube will save you money and make the diff light go away, I have not seen it since and change was roughly 3 months ago.

 

[NoClue]

We can talk about viscosities and certifications of lube all day, but what did the magnet look like?

 

[4wheelgreg]

Have changed a lot of Toyota gear oils , I just did my 2015 Tacoma new to me for precautions , looked brand new at 25k very clean . crazy thing my last GMC 3500 which never worked a day in its life I went and changed the gear oil at 10k and stuff came out nasty black yuck . Toyota always clean compared to domestic .
I always use Mobil 1 syn oils .

 

[rlynch356]

the tough thing with the Toyota oil Spec is there are very few GL5 oils in 75w-85 GL5 it seems.