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Here's the deal. The Sequoia needs to go in for an oil change this week. Since the Toyota dealers in my area are all terrible, a private garage (good reputation, years of experience) that I actually used to work at when I was a kid does the work. He only charges $10 labor to change the oil and filter with the Mobil1 and filter that we supply. I have 7 quarts of Mobil1 75W90 and planned on having the fluid changed in the front, center and rear differentials when the oil change is done.

Called the mechanic to schedule the appointment and he's questioning "messing" with the differentials and claiming it's not necessary as they are filled from the factory with synthetic. After explaining that Toyota uses conventional fluids, and restating the desire to change the fluid out for Mobil1, he said to check with the dealer to see what they advise. He seems afraid to do it, and keeps trying to make the point that it is un-necessary. My point is that once the fluid is changed over to Mobil1, it's pretty much lubed-for-life at that point and on less thing to worry about.

I can't see what the big deal is. I'd crawl under there myself and do it, but now that winter has arrived I am not inclined to do so.
 

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There is no reason not to change out these fluids. I'm with you, changing to Mobil 1 or other true synthetic can only be a positive move.

My suggestion is to go to another shop who also has a decent reputation for quality work or do it yourself. Like you said, weathers not too great to do it now ! !

Good luck.........don't let anybody talk you out of it. Its a positive move for sure.

:)
 

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Do a simple test. Drive your truck to the store and back. Go under the truck and feel how hot the differenyial pumkin is. Replace the gear oil with a synthetic. Do the same driving and "feeling" test. The pumpkin is noticeably cooler. Not scientific but enough to convince me!!!
 

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John,

More and more cars and trucks are required to use specialized lubricants these days. If your mechanic is not familiar with our Toyotas, he's erring on the safe side.

Our trucks use standard lubes, not something unique and only available from the factory. Do make the change, and thank that mechanic for his caution.

Ken
 

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John97 said:
Here's the deal. The Sequoia needs to go in for an oil change this week. Since the Toyota dealers in my area are all terrible, a private garage (good reputation, years of experience) that I actually used to work at when I was a kid does the work. He only charges $10 labor to change the oil and filter with the Mobil1 and filter that we supply. I have 7 quarts of Mobil1 75W90 and planned on having the fluid changed in the front, center and rear differentials when the oil change is done.

Called the mechanic to schedule the appointment and he's questioning "messing" with the differentials and claiming it's not necessary as they are filled from the factory with synthetic. After explaining that Toyota uses conventional fluids, and restating the desire to change the fluid out for Mobil1, he said to check with the dealer to see what they advise. He seems afraid to do it, and keeps trying to make the point that it is un-necessary. My point is that once the fluid is changed over to Mobil1, it's pretty much lubed-for-life at that point and on less thing to worry about.

I can't see what the big deal is. I'd crawl under there myself and do it, but now that winter has arrived I am not inclined to do so.
While I change the diff fluids regularly and I do switch to synthetic so that is even unnecessary, it can be argued that changing those fluids before 60,000 miles is overkill and unnecessary. Actually, I like to change it early to get the "break in" metal particles out and then switch to synthetic.

If you look at recommened change intervals on other manufacturers, you'll often find that the manufacturer doesn't even have a suggested change interval for the differentials. It's an inspection ONLY at 15,000 mile intervals UNLESS you are towing regularly, using it on muddy roads, etc where they'll suggest 30,000 miles for changes and 15,000 miles for a LSD. But for normal conditions they don't even change it, just inspect it.

Realistically, most any dealer will change the diff fluids at 30,000 as preventive maintenance, but it's not necessary to comply with many manufacturers maintenance programs. Talking broadly about all manufacturers.

So your mechanic does have a point (in that it's not necessarily "needed") but it's always good to switch over to synthetic. It has 5 times the life of regular oil and is indeed practically "forever" on a normal vehicle. (but I still change mine out at 30,000 which is overkill, I'll admit).

Even though it is okay to switch to synthetic, I'd talk to your local Toyota dealer so that you can tell the guy (honestly) that you checked with them and is okay to change the fluids to synthetic (you'll get better gas mileage, less wear and much longer fluid life).

But your mechanic is technically right that you don't need to "mess with it", but that doesn't mean you can't. There are lots of examples of diffs that failed with regular oil due to poor design but stood up fine with synthetic.


Alan
 

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I also changed my Tundra's rear diff over to mobil 1 at around 10K miles, the housing is noticiably cooler to the touch after switching to synthetic. I see it as a preventative measure, one less thing to worry about. My mazda truck had never had the differential oil changed in over 120K, never had any problems, noises, though....
 

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Change It!

I change all my gear oils (diffs, tranny, transfer case) every 20K The first time I changed my rear diff oil, it came out nasty and the drain plug was piled with little metal pieces. After the first change, every change the oil looked like new except for the 120k one in which there were four teeth stuck to the drain plug. At this point I replaced the stock carrier (with broken spider gears) with an Eaton LSD (Great decision BTW). I can not think of any good reason not to change the fluid. I also changed over to Mobil 1 at the first change. I tow an 8x16 enclosed 2 axle trailer that loaded weighs about 6,000 pounds. I frequently tow this trailer in the mountains with the OD off at about 70 mph. I don't use the cruise control though - it will stick it in second at 5,000rpm and leave it there. Even with the mobil 1, I cooked the paint off the housing while the truck was still under warranty. I also have a bad front pinion bearing - but I have well over 100k also - I replaced the carrier bearings, I should have done the pinion as well when it was apart. For comparison, I also have an F350 powerstroke (work truck) that I tow the same trailer with - it also has burned all the paint off the diff, and rusted. It has Mobil1, and a whopping 18,000 miles on it.
 

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I have to question the adviseability of using 75W90 in a rear differential designed for SAE 90 weight gear lube. I changed my rear diff to 80W90 Amsoil synthetic but I'm still not comfortable when I think about it.

The viscosity (SUS @100F) of straight 90 weight is 1122, whereas the viscosity of 75W90 is only 525 according to my Mobil data ...a big difference. The viscosity of 80W90 is 728 and that worries me too. I'll have to keep an eye on operating temperatures until I can determine that there is no problem.

Having worked with industrial gear boxes a bit, and having taught classes on bearing lubrication and prevention of bearing failures, I know it's imperative that temperatures inside the box not exceed 250F at any location because the balls and rollers of rolling element bearings begin to anneal (soften) at 250F. Shortly thereafter, the bearings begin to fail which generates even more heat. That would include wheel bearings and carrier bearings inside a rear axle.

I don't know the exact temperture at which the paint used on these differentials begins to disbond, but my gut feeling is that an operating temperature sufficiently high to burn paint is indicative of a significant lubrication failure and are more than high enough to soften the bearings. I've seen bad gear boxes that ran so hot you didn't dare touch them with your hand but the paint was still intact.

For the reasons indicated herein, I question the use of 75W90 as a substitute for 90W absent operating data indicating otherwise or a written warranty from the lubricant supplier.

Herb
 

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Herb,

My '01 Tundra calls for 80W-90 gear oil in the rear differential and 75W-90 in the front.

I see what you're saying about the variability of gear oil viscosities. The standard viscosity requirement for any SAE xW-90 or straight SAE 90 automotive gear oil is 13.5 to <24 cSt @ 100°C. (I don't have a handy converter for kinematic viscosity to Saybolt viscosity, and you're talking about the 100°F measurement which is close to the 40°C.) Anyway, 13.5 to 23.9 cSt is quite a range, but acceptable.
http://www.lubrizol.com/ReadyReference/DrivelineLubricants/15-gears/default.htm

IF...if the lower viscosity product provides equal or greater protection, then the lower viscosity oil will be OK while it generates less heat and consumes less power. For oils of identical formulation, higher viscosity provides greater film strength. For oils with different additive packages, all bets are off...each oil needs to be tested.

Here's more gear oil info if anyone's interested:
A viscosity chart showing the acceptable ranges of viscosities and where they fall in the different systems of measuring viscosity...SAE motor oil, SAE gear oil, kinematic cST viscosity measurement, Saybolt SUS viscosity measurement, etc.
http://www.bobistheoilguy.com/visc.html
Chevron Delo gear oil, an excellent mineral gear oil:
http://library.cbest.chevron.com/lu...8db00737ce8/fbf9ee13d6fb12c788256628007d0d4d/$FILE/GL-11.pdf
Some premium straight viscosity gear oils:
http://www.schaefferoil.com/data/209.html
A premium 80W-90 synthetic blend gear oil (probably equal or superior to Mobil 1 & Amsoil gear oils)
http://www.schaefferoil.com/data/267.html

Note that everything we're talking about here meets the GL-5 spec.
Ken
 

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Ken:

Many thanks for going to the trouble to post what you did.

The graphical representation on bobistheoilguy.com is invaluable because it allows for direct conversion of SUS to KV. That printed but the Schaeffer data wouldn't print.

I have an 02 SR5 4x4 with V8, auto transmission, and a LSD out back...at least for now.

Okay -- your 01 owner's manual calls for 80W90. That's good data but that's not what I see in the 02 OM. There seems to have been a change in direction and this is worrysome because a change like this invariably originates with the engineers who work for the company that designed and supplies the gear box. Toyota is merely an information conduit. That's my best guess based on what I've seen over the years and that's why I view something like this as being a red flag.

For 02 models, 75W90 is recommended for the front differential. In the case of the rear differential, both LSD and standard, SAE 90 is to be used at temperatures above 0F. Below 0 degrees F they are calling for either 80W or 80W90.

I'm using Amsoil 80W90 right at the moment. I don't know that there's anything wrong with Amsoil products but I do question using 80W90 at temperatures above 0 degrees F because that's what I see in the OM.

Yesterday, I drove 125 miles at highway speeds to a Toyota dealer other than the one where I bought the Tundra. The truck was carring no load and the ambient air temperature was in the 40's. Upon my arrival, I crawled under and placed my hand on the differential. It was hot to the touch, of course, but not hot enough to induce undue discomfort. Did the same thing with the radiator which should be operating at 180F or close to it. If anything, the radiator was just a few degrees cooler according to my calibrated 5 finger thermometer.

I tried to buy some Genuine Toyota 90W gear lube from the parts department. They didn't have any and referred me to the service department. The service department didn't have any either and doesn't use 90W. It seems that at least in this region Toyota has a contract with Mobil to supply bulk oil. From what I can determine, Mobil does not make or market a straight SAE 90 suitable for automotive applications. Service personnel told me they use 80W90 and recommended I do the same.

This bit of advice brought on a rather nasty flashback to something a Michelin dealer told me a few days ago. As far as he was concerned, the best tire for a customer's vehicle was the tire he has in stock. I can't help suspecting that I may have been hearing a variation of the same philosophy.

Right now I'm taking a long hard look at how the Amsoil 80W90 performs in terms of the observed operating temperature of the rear diff. I have in hand the Viscosity Index for Mobil products but I don't see that data for the 80W90. I called a prominent Amsoil dealer who actively solicits technical questions and asked for the Viscosity Index of their 80W90. Somehow this seems important.
I was promised a call back and have yet to hear anything. That was 2 days ago. I intend to pursue this and if I can't get a straight answer or any answer from Amsoil, come summer, if I see operating temperatures significantly higher than what I'm seeing now this stuff is coming out.

I have at least 6 months to find a good brand of SAE 90 and it may take that long at the current rate. Right at the moment Shaeffer #267 Supreme Gear Lube looks like a real possibility.

Again, many thanks for your input Ken.

Your Friend
Herb
 

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Herb,

You're right, my owner's manual also calls for SAE90 above 0°F. I think that lots of folks, including myself, are using 75W-90 or 80W-90 without problem. You can always do an oil analysis and see the extend of the wear metals in your differential oil. It costs less than an oil change, but it might be misleading if there's residual steel particles in there from the original break-in.

I may become a rep for Schaeffer oil products (no, not multi-level marketing) in the future--a couple of months away--and if I do retail and mailorder, I'll become a TS supporting vendor. The job will primarily be a rep serving large volume end users (truck fleets, mills, mining, maritime users, etc.) in my four-county area. I like their products a lot. One interesting item about the Schaeffer gear oils...they contain a tackifier that's only active up to about 75 or 80°. When the oil is cold and tends to channel away from the moving gears, the tackiness make the oil "climb" the gears as they rotate. When the oil gets warm, it loses the tackiness but it flows into the gear tooth contact point OK at that temp. If anyone is interested in those products, I'll give you links to current reps that do mailorder.
http://www.schaefferoil.com


Ken
 

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2003 Tundra Differential Oil Weight

Hello,

I have a 2003 Tundra V8 and I am looking at my owners manual.

My manual shows the from Differential Oild weight to be 75W90,
Rear
Standard Differential SAE 75W140

Limited Slip Differential

Above 0F SAE 90
Below 0F SAE 80W or 80W90,

It looks like they changed again in 2003.

Mike
 

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Mike:

Please take another look. I've never heard of 75W140. There is such a thing as 85W140. The pour point on that stuff is 0 degrees F.. That means it won't come out of the bottle at temperatures below 0F. It has a viscosity (SUS @100F) of 1980 versus 90 weight at 1122, 80W90 at 728 and 75W90 at 525.
These are Mobil numbers. Unless I'm all wet, and I could be, I see some huge differences.

Ken, what do you think?

It looks like the front differential recommendations are consistent from year to year. Perhaps we should focus on rear differentials.

One of the other things that probably should be compared are the rear axle capacities for 01, 02, and 03. If we were to see an increase in capacity (surface area of the axle housing has been increased) this an engineer's response to a gear box that is running a bit too hot for comfort.

For 02, I see the following in the owner's manual:

Rear Axle - 2wd-standard differential - 4 quarts
Rear Axle - 2wd - LSD - 3.3 quarts

Rear Axle - 4wd - standard differential - 3.7 quarts
Rear Axle - 4wd - LSD - 3.1 quarts

Does this agree with 01 and 03 capacities?

Herb
 

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KLS said:
Herb,

You're right, my owner's manual also calls for SAE90 above 0°F. I think that lots of folks, including myself, are using 75W-90 or 80W-90 without problem. You can always do an oil analysis and see the extend of the wear metals in your differential oil. It costs less than an oil change, but it might be misleading if there's residual steel particles in there from the original break-in.

I may become a rep for Schaeffer oil products (no, not multi-level marketing) in the future--a couple of months away--and if I do retail and mailorder, I'll become a TS supporting vendor. The job will primarily be a rep serving large volume end users (truck fleets, mills, mining, maritime users, etc.) in my four-county area. I like their products a lot. One interesting item about the Schaeffer gear oils...they contain a tackifier that's only active up to about 75 or 80°. When the oil is cold and tends to channel away from the moving gears, the tackiness make the oil "climb" the gears as they rotate. When the oil gets warm, it loses the tackiness but it flows into the gear tooth contact point OK at that temp. If anyone is interested in those products, I'll give you links to current reps that do mailorder.
http://www.schaefferoil.com


Ken
Yeah, Schaeffer makes some pretty outstanding stuff. They seem to be getting bigger.

Their "regular" oil is great.

Alan
 

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The Mobil 1 75W-90 is perfect for our Tundra/Sequoia rear ends. The W only refers to cold weather performance and a full synthetic flows to 40 below zero, thus the 75W winter rating. It is essentially a straight 90 weight gear oil which not only does not thicken with cold temps but likewise does not thin with high temperatures. Just about every over the road tractor/trailer you pass on the highway is using Mobil 1 75W-90 as their Eaton/Fuller/Rockwell/Meritor warranty is increased to 770,000 miles if they use it. Obviously if works in an 80,000 pound tractor trailer, it will serve us very well in our rears. (and front diffs)..
George Morrison, STLE CLS
 

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Herb,

I have double checked several times, as a matter of fact when I made the post, I had the manual open.

I just changed mine today with the 75W140. I had not heard of that weight either, but I did a search on the web earlier this week and Amsoil listed it for their synthetics. I ordered 4 quarts and it arrived today and changed it tonight. I know a lot of people are aqainst AMSOIL and I have never tried their products before I have always used Mobil 1 and will stick to that for my engine.

Here is the link to the specs:

http://www.amsoil.com/products/tgo.htm

The Gear oil is Series 2000 75W140 and has a pour point of -51 deg F.

Since my manual showed that weight I decided to give it a try.

Mike
 

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Regarding the use of a gear oil heavier than a 90W. Not even 80,000 pound over the road trucks use 140W gear oil. It is overkill to the 9's and will do nothing but create more heat, rob horsepower, reduce fuel consumption and serve no purpose. It is like the old adage if two asperins are good, four must be better.
Again, if a 75W-90 is sufficient for 44,000 rear end for a Kenworth, it is more than enough for our Tundra/Sequoia needs.
Either the Mobil 1 75W-90, Amsoil 90W, Redline, whatever synthetic will work optimally for our applications. An 85W-140, XXW-140 is just too heavy a lubricant to be sloshing about.. Not only not needed, actually deterimental..
This is from a lube engineer's perspective tho...
George Morrison, STLE CLS
 

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mpierce3 said:
Herb,

I just changed mine today with the 75W140. I had not heard of that weight either, but I did a search on the web earlier this week and Amsoil listed it for their synthetics. I ordered 4 quarts and it arrived today and changed it tonight. I know a lot of people are aqainst AMSOIL and I have never tried their products before I have always used Mobil 1 and will stick to that for my engine.
Mike
Mike,
The 75W140 is mainly used by heavy construction equipment. The heaviest weight in over the road rigs that I am familiar with use 75W90 synthetic. I would highly recommend you again drain and flush your differential housings and refill with 75W90 synthetic. I'm not aware that 75W140 will cause any type of harm but I will state that you won't get the performance from that weight gear lube that you'll get from 75W90 synthetic. The Amsoil 2000 series products are as good as they get relative to synthetic quality but the cost, money wise, of their products is what people don't like.
 

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Guys:

I think I have all this straight in what's left of my mind. Rear differential capacity hasn't changed from 01 through 03. That's a dead issue.

Thanks to Ken, who put us on to a grade system graph on bobistheoilguy.com, I noticed that the Mobil chart lacked a couple of footnotes, to wit: viscosities can only be related horizontally, and does not apply to multi-viscosity oils. Now this is making sense.

The nagging question was why is Toyota recommending straight 90 weight above 0 degrees F? That seems a bit outdated if 75W90 and 80W90 are recognized equivalent substitutes which my data suggests they are. The dealers in this area use 80W90 Mobil.

Now the nagging question is why Toyota changed to 75W140. I have to agree with George that the stuff may be entirely too stiff.
I'll bounce that question off a couple dealer service departments in this area and see what they have to say.

Mike: It might be wise to keep an eye on the operating temperature in the rear differential with 75W140 in residence, at least for a while. The radiator operates at about 180F providing a convenient reference datum that can be used to feel any significant difference in operating temperatures absent a rear axle temperature gauge. Keep in mind that the rolling element bearings inside the differential will begin to anneal (soften) at 250F. It takes more Work input to the differential to spin the ring gear through heavy oil. The same is true for bearings. This additional work generates heat which must be dissipated.

Joe: It isn't the price of Amsoil products that bothers me. When I placed an order with them over the phone I got the distinct impression they were doing me a huge favor. I specifically asked for a dealer list which they agreed to provide. That was 2 weeks ago. So far, nothing.

George: I received the magnetic drain plug and 75W90 I ordered from you in 2 days. The drain plug is impressive. Thanks for the good service.

Herb
 
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