Gear Oil 75W 90 or 75W 140

Had the gear oil replaced today at Toyota dealer. They recommended and used 75W140 instead of 75W90 in my 2006 Tundra 4.7 Dc 2 wheel drive. I know the owners manual recommends 75W90. The truck has 162550 miles on it with no known differential problems. Its used mostly for short trips around town. Any members using 75W140 or have opinions as to its use in high mileage vehicles?

 

I'd want to know why they're recommending it. Choosing the right oil for an axle or a transmission is a compromise because you have two potenial wear/failure points that have very different demands: the bearings and the gears. The bearings would last longer if the axle was lubricated with 30W motor oil, but the gears would wear much quicker. A thick gear oil protects the gears, but at the expense of the bearing life. The trick for the engineers is to find the balance that provides acceptable protection/performance for both.

I don't recall hearing of anyone on this forum (or the 4Runner forum when I had a 4Runner) with an internal axle failure unless it was run low on fluid as a result of leaking... and there are many members with 300K + miles. So it would appear the Toyota engineers found the right balance with

$39 75W-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75W-90. Would 75W-140 provide better protection for the gears? Probably. Would it provide less protection for the bearings? Probably. Would it make a noticable difference in the longevity of the bearings? Who knows... but probably not. If the dealer says they've been seeing oil related axle problems then maybe consider their recommedation -- but I doubt that's the case. Personally, I'd still stick with the recommended 75W-90.

And just to be clear, the axle bearing failures we do hear of somewhat frequently are the outer bearings, which are sealed, and not lubricated by the gear oil in the axle.

 

I did redline 75w140, my truck has 330k so it was recommended for higher mileage by basically everyone that I talked to that knew about our trucks.
Toyota tech to some drivers I know from trails.
Just thicker with more protection for worn gears was the overall consensus that I got.

 

y of the bearings? Who knows... but probably not. If the dealer says they've been seeing oil related axle problems then maybe consider their recommedation -- but I doubt that's the case. Personally, I'd still stick with the recommended

$39 75W-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75W-90.

And just to be clear, the axle bearing failures we do hear of somewhat frequently are the outer bearings, which are sealed, and not lubricated by the gear oil in the axle.[/QUOTE]

Checked back with the service tech. He said that my truck not having limited slip differential is the reason for the 140. I looked again in the manual and he is right Recommended oil viscosity: Front SAE 75W−90 Rear Standard differential Synthetic oil SAE 75W−140 Limited−slip differential Above −18C (0F) SAE 90 Below −18C (0F) SAE 80W or 80W−90. On a positive note.. The clunking sound from the rear seems to have stopped since the gear oil change. At least it did not happen during the hour I drove around today.

 

I remember hearing the LS needs 75-90 and open riffs calls for the 75-140. I think you'll be fine.

 

^^ This would seem to indicate the opposite of what the tech said...?

 

Maybe '06 is different than my '00. But my manual says

$39 75W-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75W-90 for the front diff and transfer case, 80W-90 for the rear diff. (no mention of limited slip... perhaps it wasn't offered in '00)

For simplicity sake, I just use 80W-90 in all 3.

 

80w90 in rear. 75w90 all others

 

Your reading it wrong because it is not punctuated correctly. The first number is for the front Diff and so on...

 

Likely. The simple yet important inclusion of punctuation is a dying art in the world, particularly among a generation that learned to type with their thumbs rather than fingers. I am clearly getting old...

 

4 quarts right? 4x4 2000
What brand did you use? Full synthetic?

 

I use the Lucas 85w140 in the rear and have since I first dealt with ECGS about 12 years ago and talked with them about it. 75w90 in transfer and front diff.

If you don't live in an exceptionally cold place - you could even consider bumping that 75 weight up.

 

Oh boy, here we go again...

Trust me on this, as someone that went thru a wild ride no this one recently. Don't listen to others on what they're using without some considerations.

Capacities vary between trucks, even within the same year. It's best to look up your specific year. Dont' trust what anyone else did. Do your research, either by consulting the Owner's manual, or looking up capacities at one of the popular sites, I recommend Amsoil's site, or Lucas' site to do the lookup.

Before anything though, you'll want to check if you've got LSD in the rear. There'll be a sticker on the back of the pumpkin, assuming your rear axle housing is stock, and you're not in a rusty area where the sticker has rusted off.

If you have LSD, what you install out back is different. The LSD in these trucks is prone to chatter if you use synthetics, even with additive - this is what I learned the hard way, despite a couple people on here trying to warn me. I went 75w140 synthetic Mobil1 in my LSD rear, and got chatter galore, even after adding multiple ounces of slip additive. Synthetics just don't coat the same.

I found no problem with running full-syn Mobile1 75w90 in the transfer case and front diff. To get rid of chatter out back, I had to go dino oil, 80w90 Lucas. but I have LSD rear end.

Be careful not to overtorque on the transfer case plugs.

Be careful to always attempt removing the drain plug BEFORE the drain plug, and sorry if you already know this, if you already know, then consider this as "advice for the next reader looking for info".

I recommend getting a new crush washers for the rear diff. I'll find the damn washer diagram in a sec.

Note for any plug that's using an allen-head drain plug, two things: (1) If you strip it, there's an additional torx thread a bit deeper in the hole, and (2) you can swap out for a standard bolt head using a Lexus part, info here

 

75w140 can't harm it, though you may notice a bit slower acceleration and worse MPG. I used Amsoil 75w140 instead of factory 75w90 in my battle wagon for long overlanding trips with ton of load, can't complain. Once the gear oil is heated up even MPG is back to almost normal. It is cold trips that make MPG drop noticeable.

 

Here's an example of what I mean when I say look up capacities at Amsoil's site, this is what it looks like, just follow the notes they give and they'll tell you all the capacities based on the model/submodel you select: https://www.tundras.com/threads/1st-gen-lunch-table-general-discussion.60450/page-1404#post-3047402

Here's a link to the part numbers for the washers - The flat gaskets don't need to be replaced if this is your 1st, 2nd, mabye even 3rd time, but you really always want to replace crush washers to get proper seal. https://www.tundras.com/threads/1st-gen-lunch-table-general-discussion.60450/page-1404#post-3046141

I'd also recommend checking the drain/fill plugs after a few days and/or few dozen miles to confirm no leaks. sometimes it can be hard to tell with the read diff drain specifically since it's pointing downward.

And to that point ...

Yes, it absolutely can if the guy asking is in the deep north. For someone living in Alaska, with heavily cold winters, they probably don't want to listen to the same weight advice as someone in Florida because 75w140 won't operate the same in different climates. It's the only thing that bothers me about peopel giving lubricant advice on internet forums.

(and also bugs me when people don't put their general location in their profile for members to reference)

 

It is coldW-hot.

Gears will be fine, they are partially submerged into oil and lubricated enough even when the oil is nearly frozen. When the gear oil is fully frozen you have other headaches with keeping your car running in such temperatures

Long term, the bearings can be damaged if all the vehicle is doing is short trips, because they are splash lubricated. No splash, no lubrication. But diff oil heats up pretty quickly, as shown in this video: https://www.youtube.com/watch?v=vmuEKqZ685s It takes very little time for oil to start splashing again in -20 F weather.

 

Dammit you're right and I dunno why my brain was thinking about it in the inverse, because I havent' done that in the past. Correcting that now so I don't confuse someone later.

But point still stands: I'd still use a lighter weight oil farther north. Despite how fast it warms up.

 

Me too!

 

did you have to add any LSD additive to the 80w90 Lucas gear oil ? Doing my diff tomorrow. I also have an 06 with LSD.

my plan is to buy 4 qts of Lucas 80w90 and a bottle of KW LS additive

last time I did it (35k miles ago) I used full synthetic Valvoline

$39 75w-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75w-90 with the lsd additives in it already.

 

No additive. Lucas 80w90 worked perfect. I still can't believe how bad the Mobil1 full synthetic 75w110 was. Last time I doubt anyone on fluids when stern warnings are given...

 

$39 75w-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75w-90 Amsoil is about the best gear oil you can run. Personally I run 80w-90.

Costco Mobil 1 5w-30 in all 7 of my vehicles.
80w-90 Amsoil in all diffs and T-Cases
Redline MT-90 in all Manuel transmissions.
For Auto Trans, Factory Fluid (WS)

 

It depends what you have. 2WD w/o LSD calls for 75/140. LSD follow Shifty’s advice

 

Im currently on about 5k miles w/ Lucas 80w90. 06 dc. LSD. Nothing else added. Runs like a effin champ. No clunks or slipping. I will say I had to go to 3 different autozerns to find 4 quarts though. 80w90 isn’t a common weight I guess.

 

Conventional 75w110/140 would be fine in the LSD diff as well.

It's synthetic it doesn't like.

 

Dino for the win!

 

Thank you all. Knocked it out today. Added new crush washers

the fill plug was a pain to get off. It took about 3.5 quarts. Had to drop the spare tire to fill it up easier.