I was curious on what type of gear oil do you all use when you change out the differential oils (front and rear) and the transfer case oil.

Synthetics (75w-90) will run about $7 a quart.
Regular 75w-90 gear oil runs about $3 a quart.
Since I'll need about 5 quarts total to replace the fluids in the differentials, synthetic can be pretty pricey.

Is it worth the extra $ for synthetics? Any empirical data to back it up?

J

 

I run synthetics in some of my rigs

Cherokee: in front and rear and transfercase (Required in diff for trailer towing).

Landcruiser: All Dino oil (petroleum) because it gets deep in water at least once a year and needs changing

Toy 4X4 Running synthetic in rear (note: the case is cooler when running the synthetic)

No real data except the cooler rear end

I think I was only paying about $5 qt at NAPA

 

Thanks "Master Yoda"

J

I searched the forum and it seems that a lot of Yota owners use sythentic. I go off-road anytime I have the chance and play in the mud when it rains, so it's probably most wise to use synthetics.

 

I recently also switched all my diffs and t-case to fully synthetic Mobil 1.

 

For me, when it comes time to change the differential oil in my axles, it will cost me a lot for synthetic, convientional is already expensive enough for me at 5 quarts for $40 (because of the limited slip). $80 for both axles (4WD) at convientional, I wonder how much for synthetic...:eek:

 

__________________________________________________ _
The cost will be the same - you only need 6 quarts for your Tonka Tundra - 3 for the rear, 1.2 T-case and 1.2 for the front. $9.00 a quart for the Amsoil 2000 75/90 gear lube. You'll probably see .5 to .75 MPG improvement on the switch so you'll be money ahead as the synthetic only needs changing every 200K unless you get water in the diffs.

 

Fluids I use

 

I read my Powertrax manual, and it calls for 85W-140 unless in very cold situations, in which I am not. I am writing this because I just saw Mobil 1 75W-140 synthetic for $15.99 per quart. The Mobil 1 75W-90 synthetic was only $7.99. I would like to use a synthetic gear oil, but find Mobil 1 too expensive. I thought about it for a while, and I can not figure why this heavier weight causes such a price increase. Amsoil is $12.50 per quart for that weight and $7.99 for 80W-90. I will try Amsoil because of all the good posts I have read.

 

I use synthetic oil (Red Line 75W90) for the differentials and transfer case.

 

Here is what I use:
http://www.4crawler.com/4x4/index.sh...ntheticGearOil

I found a noticeable difference in operating temps between conventional and synthetic in both axles and t-case/tranny. Both used to get so hot that you could barely touch them, after switching to synth. they are still hot, but you can keep your hand on for a long time. Guessing a 15-20F temp reduction. I also like the Redline shockproof oil for my diffs, it is super sticky. When you are idling along at 200:1 gearing, it can take 15 seconds or more for the ring gear teeth to leave the oil in the bottom of the housing until they contact the pinion gear teeth. I had a housing I pulled out of my truck and 2 years later, it still had a visible film of shockproof oil on it.

If going to synthetic, make sure you have good, raised diff breathers to keep the water out. If you do lots of deep water and mud, you may want to stick to less expensive conventional oil and plan on changing it as needed.

 

I'm running Mobile 1 Synthetic 75W90 all the way around in my '04 Taco and it does seem to keep things a bit cooler. I've also noticed the 5sp is a little harder to shift on cold mornings (well, cold for So Cal) as I'm pulling out of the neighborhood. Don't know what that's all about or if it's even due to the fluid change.

 

Mobil1 is a GL5 gear oil. A good GL4 oil will work better in the tranny. GL5 oils are too slippery for good synchromesh operation. The extra slippriness makes the synchros slip longer, making shifting sluggish. A GL4 oil is not as slippery and will help the synchros grab better, making for faster shifting. I noticed a marked improvement in shifting in my '85 5-speed when I went from GL5 to GL4.

 

Well, there you go! I'll take a look at the GL4 oils when next it's time to change fluids (which wont be too long here). Thanks 4Crawler.

 

I use synthetic everywhere except the front diff. If you're not using it that much why put synthetic in it?