Is there a consensus here on differential oil?

The topic is differentials, not transmissions.

 

Read the OPs original post. He asked about tranny and diff fluids.

 

I have a 6 speed so have to do all 4 cases. Ill probably do redline or amsoil all the way around

 

Lots of people think that higher viscosity oils and synthetics are nonsense. Here are some facts that people can use to make up their own mind.

1. The higher number in viscosity rating measures the viscosity at 212 degrees.
2. between 212 and 257 degrees, gear oil loses half of it's rated viscosity. SAE 140 is about double the viscosity of SAE 90 at 212
3. A Tacoma running mostly empty in the summer will run typically between 150 and 175 degrees. Add mountains and you will see 200 to 220. This is why most are fine with

$30 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90
4. A Tacoma towing or hauling in the summer with moderate grades will see temps from 220 to over 250 degrees
5. Once the heat starts building it almost becomes a runaway. The diffs have no cooling beyond their surface area.
6. These numbers are with synthetic oils. Dino will run around 15-20% higher
7. A Tacoma that is running lower gears will likely see higher temps yet, because everything is turning faster.
8. These numbers are for a Tacoma. A truck with an appropriately sized ring and pinion will not have this liability.

So basically, a Tacoma that is working hard in heat needs 75W-140 to get the same viscosity under load as an empty Tacoma gets running 75W-90. The higher viscosity will suck MPGs when running at normal temps, but it has clear advantages at the real world temps that these trucks see when run hard. Would you rather save a little gas or save your gears? I can only make that judgement for myself.

 

I stand corrected

Food for thought. Mine gets run pretty hard. Where were you able to find such specific numbers for the Tacoma?

 

Seems to me you can put Royal Purple, Redline, Severe gear in the same boutique fluid category- I dont think you go wrong or as mentioned pick your color- I have only used Redline and have seen noticable difference when used in the tranny so I stay with it. I personally started to lean to the lighter side of the weights- 75 vs 85 for example if there is option in product line-when I buy these kinds of products. I am putting my confidence in the quality of the products and its additives and a lighter weight for the MPG advantage. That is what "I" do but its just an oil change your not married to the decision-

 

I run Lucas 85W140, non-synthetic, in both difs. Price is good, easy to find in stores, and ECGS told me to use it.
Armor and big tires are heavy enough that i consider it almost like towing full time and follow the special conditions maintenance schedule.
No noticeable difference from when i had Amsoil in them.

 

Another vote for MT-90 in the 6spd trans. Made world of difference in my last taco.

Don't forget to order the new crush washer kit before changing out all the fluids.

 

Very valid point I hadn't thought about!

 

When I installed the locker and gears, I installed a temp probe and started recording data. That was about 6 years ago and about 125,000 miles. Prior to that I used a laser probe, but that is really hard to get real time data because the temp drops fast once you stop the truck. The temp numbers are all my own. I did this because I saw signs of overheating in the diff when I changed the gears. I knew the R&P was marginal with the weight of the truck and the HP already, so I wanted to actually know what was going on. Your truck runs pretty much fully loaded all the time right? I know you use it too. It has been a real learning experience. I could see the excess heat during break-in, and I knew when the break-in was complete. I knew when to stop and let it cool. I could also see the differences between dino and synthetic. I use Redline in the diffs mainly because I use Redline in the transmission and T-case. I also know people in the racing world who use it. There are other good options for the Diffs though. I'm not a fan boy except when it comes to Redline in the transmission. I'm hard line on that.

 

Yep, loaded all the time and towing regularly. Lots of mountain driving.

I know ECGS recommends Lucas Dino oil in the heavy weight when the set up gears and lockers. Are you suggesting the redline is better, even for my applications? I have some for the overdue tranny oil change. I'm not due for the diffs right now. I just did the Lucas Dino in the rear and M1 in the front.

 

M1 is fine in front. It never sees the heat that the rear does. Lucas is good oil, but I just don't like dino in the rear on this truck because it absolutely does run hotter. At least you are running a 140, so you are probably protected enough. Your call. Maybe switch next change? I like Redline or Amsoil Severe gear the best. I've tested a bunch of them, and the differences between synthetics are pretty small. The difference between dino and synthetic is much bigger. Definitely though, MT-90 in the tranny.

 

How did you install the temp probe? What type did you use? I'd be interested in doing this on my truck as I am curious about the types of temps my truck is seeing. Any more info on the subject would be much appreciated.

 

I have the short throw shifter in my 6-speed and I definitely noticed smoother shifting when I switched the transmission to Redline MT-90 after a round of Mobil 1, the Mobil 1 felt stickier especially when it was cold out which was really noticeable with the short throw. I still use Mobil 1 in the differentials because it seems to work just fine and is easy to find locally (and on sale). I order the MT-90 special when I'm changing out the transmission.

 

You need to drill and tap the housing to thread in the probe, so it's best done when you have the gear set pulled out. Mine is an Intellitronics, but any good brand will work. I think the thread was 1/8" NPT. Of course you also need to make sure it doesn't contact any moving parts. I have an ARB locker, and found a spot on top of the diff near where the air port goes through. You might find a contact type sensor too, but the internal probe will be more accurate.

 

He's talking about the M1 LSD gear oil, not motor oil. Mobil 1 makes different types of oils.

 

Thanks Badger

 

U think MT-90 is better than Amsoil manual tranny fluid for the tranny and t case?

 

Yes. I tried both and I got better results in the transmission, so I use it for both. I couldn't tell the difference in the transfer case. I think the two take exactly 3 quarts, so it makes it easier to do both with one oil.

 

Not here to tell anyone which lube to use, however I want to share an article I ran across many years ago.

http://www.lastgreatroadtrip.com/wp-content/uploads/2010/11/gear-oil-comparison.pdf

It's dated (2007), but I believe a lot of the data to be useful in my own decision making.

I used Amsoil severe gear in my 2010 5-lug 4x4, 6spd, tranny, xfer case, and both diffs. It moves, drives smooth, shifts smooth, no complaints.