Differential Fluid: Syn. or Conventional

[Whitey]

Time (overdue) to change the diff fluids in my '00 4runner.
Is there a need to pay 2x as much for synthetic? Are the lubricity demands of the diffs. equivalent to that of an engine?

 

[BLKNBLU]

I've recently been wondering the same. In fact I'm finding 4x the price for the 85-140 that we like here in the desert heat. What if we could change oil 3x more often and still save $$. Of course there is the PITA factor of more frequent changes.

 

[Whitey]

You bring up another point worth mentioning. I'm from MA, but I just moved to Dallas. I'm actually flying home to get my truck next week. Should I go with a different weight than factory spec, being in the heat?

 

[Martyn]

I changed all of my lubricants to synthetics. My fuel consumption went from 16.5 mpg to 20 mpg. I think that synthetics in the drive train are key to this.

 

[Dave Bennett]

I changed all of my lubricants to synthetics. My fuel consumption went from 16.5 mpg to 20 mpg. I think that synthetics in the drive train are key to this.

That's all I needed to hear. With my 60,000 mile service coming up I guess that would be the time to do this. Now to figure out which ones to use.

 

[TangoBlue]

I use synthetics throughout and my mileage went down!?

Well, maybe the armor, suspension, lift, larger tires, bumpers, and assorted trail gear had a little influence, too.:yikes:

 

[Martyn]

That's all I needed to hear. With my 60,000 mile service coming up I guess that would be the time to do this. Now to figure out which ones to use.

Doc

I used Amsoil

 

[Rexsname]

Mobil One here.

I did not notice a mileage difference but I feel better knowing that I use the best. (puts on flame suit)



REX

 

[DaveInDenver]

I've used synthetic in my engine for a long time and never really gave much thought to the gear lubes. A year or so ago I went to Redline in the drivetrain, didn't see a huge jump in mileage but my tranny does shift better now (it's 225K miles old!) and the rear diff is noticeably cooler after being on the highway. The housing is often barely above ambient temp and rarely is too warm to hold your hand on, where before it would really hot after highway speeds. It is noisier though, more gear noise than with dino lube, dunno.

 

[Cabrito]

I recently went to full synthetic in my Engine, T-case, and Transmission.
170k on the rig at the moment.

It is possible that I noticed a slight increase in MPG but with all the variables in that equation it's hard to tell for sure.

I did notice a slight performance increase for sure.

Haven't done the diffs in a while. Perhaps that is next.

Redline all around by the way.


..

 

[ntsqd]

An observation on synthetics, or at least Redline synthetics.
I bought a used W-56 from a friend who had Redline in it. It had sat with the drain plugs out of it for more than a year before I got it. I got it home and it sat for 8-9 months, weeping reddish-pink stuff onto the garage floor the whole time. I used the transfer case off of it to be part of my Marlin doubler, so now the W-56 is sitting on the floor open at the rear. For the next 6 months it continued to weep reddish-pink stuff onto the floor. After being open for coming up on 3 years there is STILL oil in the nooks and crannies of the trans!
The oil does not appear to be some uber high viscosity stuff. It just does not like to let go of metal.

I'm sold! Don't really care if it increases my mileage or not. If it does that will be gravy, if it just makes wear parts last longer I'll be happy.

 

[hillbillyjake]

has any body thought about using the cheapo synthetic from wal-mart or the like. it is cheaper than the name brands. i dont know the quality of it but i would assume that it is made by brand name manufacturer. just a thought.

jake

 

[shawkins]

I have been running Mobile1 in the engine since I bought my 4Runner at 100K, it has 130K now.

I also just put Mobile1 in the rear diff when I put in my e-locker. I couldn't really tell a difference because I also changed gear ratios at the same time.

The tranny is next to get changed, but I can't decide between MT-90 or Mobile1.

 

[ryguy]

I use amsoil and have for for the past decade. I put severe gear 75w90 in my diffs and t-case, low viscosity atf in the trans, and run 25k syn 5w30 in the motor and it feels like a different truck. Well worth the money

 

[CA-RJ]

I've been running Mobil 1 synthetics in the drive train for about a month now and noticed no increase in fuel mileage, but it's nice to know that the protection is there. I change the fluids once a year, so it's worth spending a few extra dollars to me.