any hard data avail on benefits of mobil 1 in diffs

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I am a firm believer in better to spend a little now than a lot later. With that said, any hard evidence of less wear or better gas mileage when using M1 in diffs?

Seems like Raven or someone would have done a mail in study. Did a search could not find.

wd
 
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The diff's call for 80/90 in my book. M1 is 75/90 and is very thin.
Some use it though.
I use Amsoil 80/90.

I think any oil will be OK as long as you change it once in a while.
The Toyota diff are well made.
I rebuit my front diff only becouse I thought 200,000 mi was a good time to rebuild it. It was a waist of time, the bearings were still in good shape.
I have a kit fot the rear diff but will wait another 100,000 or so mi before I pull and check.
 
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I've used M1 since the first diff changeout and my diffs are quieter than other 80s I've been in. However, it's a very subtle thing and has no impact on the durability of the diffs. I suspect the same slight difference in wear could have been achieved by aggressive changing with ordinary oil. I did it because when I bought the truck in 93 I planned on keeping it for a long time. Now it's paid off as I have extended that to keeping it forever....

DougM
 
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The short answer is no, you will not find hard data. In fact, you'll be hard pressed to find hard data supporting any product above and beyond what's specified as the requirement in the manual.

I personally believe the placebo effect is rampant for car maintenance enthusiasts and, especially for well-built vehicles like Toyotas, if you follow the prescribed intervals you will likely not find any significantly different longevities than the fanatically anal.
 

Onur

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I use the M1 in the xfer only;

I used CruiserDrew's advice in an earlier post and bought a 5gal bucket of Coastal 80w90 and basically swap out the old and in with the new every 2K miles or so (sometimes 3-4K depending on the type of driving I've been doing).

This method seems to do well and keeps costs down while still putting fresh juice inthe fr/rr as needed.

The xfer I change out every 8-10K miles when I do an oil change.

Best.
-onur
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again, no hard data here, except that when i bought our '97 about 2 months ago, it had dino in it and i ran a few tanks thru it to the tune of 13.5 mpg city and 15-16 hywy.

have since put amsoil 80/90 in fr and r diff and mobil1 75/90 in xfer (the exact weights specified) and now see in the 14's for city. haven't done any hwy since. unfortunately for this test, i also increased air pressure to 35. in car after car, i find that running 3-5 psi over the mfr pressure gives noticably better mileage and think this has a larger effect than gear oil differences.
 

Cruiserdrew

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beno said:
I use the M1 in the xfer only;

I used CruiserDrew's advice in an earlier post and bought a 5gal bucket of Coastal 80w90 and basically swap out the old and in with the new every 2K miles or so (sometimes 3-4K depending on the type of driving I've been doing).

This method seems to do well and keeps costs down while still putting fresh juice inthe fr/rr as needed.

The xfer I change out every 8-10K miles when I do an oil change.

Best.
-onur
Akron, OH
That's a lot of diff oil changing! If I remember, my advice was to use the cheap stuff to clean out a grease or water contaminated front end. After it's clean, I use Chevron Delo Gear ESI 80w-90, and that's what is in all of my trucks right now. I used to use Mobil1, but I ended up changing the diff oils several times a year, and that was too expensive to use. Even the Delo gear is expensive now. A year ago it was $3 a quart in bulk, now costs $4 a quart in bulk. Highly reccomended stuff though.

For the T-case, I use Mobil1 and change yearly regardless of mileage.
 
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landtoy80 said:
The diff's call for 80/90 in my book. M1 is 75/90 and is very thin.
Some use it though.
I use Amsoil 80/90.
Please explain why 75w-90 gear oil is "thin" compared to 80w-90? Last I checked both had the same CST at operating temperature. BTW, would you care to guess where Amsoil buys all their group IV basestocks.

As far as objective evidence for synthetic gear oils working better than mineral oil, the only place I have seen this is in road race cars. Those diffs are worked very hard and see very high operating temperatures (often 300f). In those applications there is a signficant increase in life, often rear ends will go the entire season instead of 1-2 races. Keep in mind, you are looking at an application where the differential is seeing anywhere from 100%-300% of it intended load and the car is being run at full throttle much more than any road car.

Street driven vehicles that are not overloaded, there seems to be no difference. I will say for manual transmission cars, Redline MTL much improves shifting, especially in cold weather, because 1) Synth is more stable over wide temperatures, and 2) Redline put friction mofieres in their MTL to allow the syncros to grab instead of slip by.

Cary
 

Onur

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Sorry to misquote Drew--yuppers, you are correct--the cheap dino to flush out the diffs. (just rechecked my saved URL).

But at $23 a 5gal, I still don't mind switching them out more rather than less...peace of mind for me and not too bad on the wallet either. Stuff seems to work fine.

Thanks for the correction.
-o-
 

Cruiserdrew

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beno said:
Sorry to misquote Drew--yuppers, you are correct--the cheap dino to flush out the diffs. (just rechecked my saved URL).

But at $23 a 5gal, I still don't mind switching them out more rather than less...peace of mind for me and not too bad on the wallet either. Stuff seems to work fine.
-o-
I totally agree. With the Delo Gear pushing $75 per 5 gallons, the FJ40 may have to get by with the Coastal. The Mobil 1 is $150 for 5 gallons!!! The FJ40 is the truck I tend to have in deep water, and a gear oil change is cheap insurance when returning home.
 
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Cruiserdrew said:
With the Delo Gear pushing $75 per 5 gallons.
Wow. I bought my 5 gal bucket about a year ago, and it was a little over $50. I'll try and double check my source tomorrow, to see if you're getting hosed or prices have just changed that much.
 
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whodat said:
I am a firm believer in better to spend a little now than a lot later. With that said, any hard evidence of less wear or better gas mileage when using M1 in diffs?

Seems like Raven or someone would have done a mail in study. Did a search could not find.

wd

I have not done nor seen any UOA's on gear oil, there was some info ON BITOG about beter fuel economy with synthetic, both by forum members and in an SAE paper, (only a few % diffrence) I did the math at the time and it was not enough to pay for running synthetic engine oil but transmission and diffs stay in much longer and may have a chane to break even cost wise

some mnufacturers are starting to run synthetic gear oil from the factory in rear differentials, the assumed reason is CAFE, GM charges $25/quart for thiers, I guess they are trying to recoup the cost of the factory fill. it can be mail ordered for $16/quart

I run M1 gear oil for same the reaon I run M1 engine oil, it is a commonly avaialable true synthetic. the front was the last to get it, it got many dino flushes first to get rid of the grease residue. (should have done the breather mod earlier)
 
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<<<<Please explain why 75w-90 gear oil is "thin" compared to 80w-90?>>>>

Just pour some out. The 75w90 is like water. The 80/90 is like syrup.
Not very techie but I will go with what the manual calls for.
 
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landtoy80 said:
<<<<Please explain why 75w-90 gear oil is "thin" compared to 80w-90?>>>>

Just pour some out. The 75w90 is like water. The 80/90 is like syrup.
Not very techie but I will go with what the manual calls for.

I assume youo are using Amsoil 80-90 GL-5?

Kinematic Viscosity @ 100°C, cSt (ASTM D-445) 14.9
Kinematic Viscosity @ 40°C, cSt (ASTM D-445) 116.2

Viscosity Index (ASTM D-2270) 132

Mobil 1 Synthetic Gear Lubricant LS 75W-90

Viscosity, ASTM D 445
cSt @ 40ºC 106
cst @ 100ºC 15.2

Viscosity Index, ASTM D 2270 150

So Mobil one is slightly thicker than at room temprature and slightly thinner at operating temprature

the diffrence is very little in both cases
 
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I was talking about M1 vs dino 80/90. Maybe its the dino vs syn gear oil???
I did a pour test. I put Valoline 80/90, Ams 75w90 and M1 75w90 on a pan.
The Ams and M1 flowed fast and the Val flowed slowly.

It might be the drain temp. WHen I drain the t-case, the M1 flowed like water and the diffs take for ever to drain. THe t-case must be hotter when driving.

Anyhow, why would Toyota call for 80W or 80W90 below 0°f and 90 for above 0°f in the diff's and 75W90 in the t-case?
Even with 80W90, its too thin above 0°f (per the FSM). That said, the 75W90 is even thinner.
We should use 90W in summer.
Where do we 90W oil anymore???
 
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landtoy80 said:
I did a pour test. I put Valoline 80/90, Ams 75w90 and M1 75w90 on a pan.
The Ams and M1 flowed fast and the Val flowed slowly.

It might be the drain temp. WHen I drain the t-case, the M1 flowed like water and the diffs take for ever to drain. THe t-case must be hotter when driving.

Anyhow, why would Toyota call for 80W or 80W90 below 0°f and 90 for above 0°f in the diff's and 75W90 in the t-case?
Even with 80W90, its too thin above 0°f (per the FSM). That said, the 75W90 is even thinner.
We should use 90W in summer.
Where do we 90W oil anymore???
As raventai just showed by posting the CST's of the oils, 75w-90 is no thinner at operating temperature than 80w-90, or for that matter straight 90 weight. The first number refers to cold pumping, the second the thickness at operating temperature. If you could make a 10w-90 gear oil, it would still be the same thickness as a 80w-90 at operating temperature.
 
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