Any reason to NOT use synthetic oil in the axles?

[AwesomeJ10]

Talking about axles here, not engines.

Any reason (other than cost) to not use synthetic oil in axles? None of my rigs have any type of 'limited slip' so they don't have the requirement for an additive.

Just curious.

I've noticed that the 14 bolt in my J10 get's super hot (to the touch) when on extended hwy runs. Will synthetic help with that?

[Stuka]

Provided you do not have a limited slip, there is no reason outside of cost. It is superior in every way. Just about every new vehicle uses synthetic these days because of how much longer it last.

The gears may run cooler with the better lubrication that synthetic provides. And synthetic holds up to heat much better.

But man is it expensive compared to dino lube.

[Mars]

Non really other than the reasons Stuka pointed out. But honestly how often do you change out the diff lube? Maybe I'm a bad owner but I can count on one hand how many times I've done on the many vehicles I've owned. If you wanna do it, do it. It's not like youre asking about all the wonderful benefits of Royal Purple

[Stuka]

Non really other than the reasons Stuka pointed out. But honestly how often do you change out the diff lube? Maybe I'm a bad owner but I can count on one hand how many times I've done on the many vehicles I've owned. If you wanna do it, do it. It's not like youre asking about all the wonderful benefits of Royal Purple

Never changing it is more of a reason to go with synthetic as it last significantly longer than standard gear lube. Which is why most new cars use it, it last longer.

[lindel]

If you go to Currie's website, they'll tell you not to use synthetic in their axle assemblies, or they'll void your warranty. They say because they'll overheat. I've checked all the other axle manufacturers that I can find/think of, and NONE of them agree with Currie that I can find.

That said, I'm using Amsoil 75w90 in my axles, Amsoil 75w90 GL4 lube in my transmission and Amsoil synthetic ATF in my transfer case, not to mention the Amsoil 10w30 in my engine.

The research I've done tells me that all of the axle manf. for the big rigs don't have any problem with synthetic lubes in their axles. Last time I checked, the big rigs put just a small amount more stress and strain on their axles then you could put on a Currie axle.

My $0.02, and YMMV...

[REDONE]

The only time NOT to use synthetic is for the first 500 miles of break-in on new gears. I don't know what Currie's site says, but I trust Lindel's evaluation of it.

The reason to use cheap dino lube during break in is so the gears will wear-match to eachother, which is essential to long term life of the gears. If you fire it right up with synthetic, they might not wear-match and that can cause higher operating temps through the life of the gears, thus shortening over all gear life.

Past that there's only one other reason, and that's if you get in your gears every few months because you're a compulsive tinkerer. That just goes back to the cost thing you said not to bring up, so strike that last part. /:)

[AwesomeJ10]

It's interesting to hear that Currie doesn't like synthetic in their axles. Aren't they one of the leading axle manufactures for the offroad aftermarket?

Hearing stuff like that makes me wanna just keep what I have in there as it only has a couple thousand miles (but those are hard miles).

[Stuka]

Not sure why Currie says not too, outside the break in period. But Being that manufacturers stick synthetic fluid in their axles and doubled the change interval, I think that's proof enough that it works fine. And that includes the break in period.

Synthetic oil has been proven to handle heat and shear better and not break down as fast.

However if you change your fluid yearly or the like (wheeling makes stuff get dirty quick), don't bother with synthetic.




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[REDONE]

And that includes the break in period.

OEM diffs are wear matched at the factory, at least at Dana and AAM they are. When you toss your own gears in from Yukon or Richmond they are not. I learned a lot about this when I was trying to get hired on at Randy's.

[Stuka]

Well that is true. So it isn't a true break in. But looking past break in, I still say synthetic is fine. Currie may be against it, but Dynatrac is for it.


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[REDONE]

Totally, synthetic for everything! When I had a mustang every drop of lube it got was Mobil1 synthetic, my Saturn; Redline, My PowerWagon; SupertTech, my race trucks; Royal Purple.

My favorite was Royal Purple, but not because it proved to be better than other synthetics while I was using it, they just had a really awesome sponsorship program back then and I got lots and lots of free oil from them.

[AwesomeJ10]

I almost wanna do a control study while driving the J10 down to Las Cruces;

Drive a few hundred miles on the fluid that's in there, check the temp of the diff.

Change out the dyno oil for some Amsoil, then drive another few hundreds miles, check the temp....

[Mars]

So I guess I'm a bad owner.
I've always done the pinky test. If you stick your pinky in and it comes out wet, youre good.. that sounds dirty..
I don't think I've ever actually changed fluid unless it's contaminated or gone. Course I don't drive under water or do any sort of real wheeling.
And I'm talking mostly from my lead sled street car experience here. Never messed with truck axles other than to tinker with springs.

Mike

[ClovisMan]

So I guess I'm a bad owner.
I've always done the pinky test. If you stick your pinky in and it comes out wet, youre good.. that sounds dirty..
I don't think I've ever actually changed fluid unless it's contaminated or gone. Course I don't drive under water or do any sort of real wheeling.
And I'm talking mostly from my lead sled street car experience here. Never messed with truck axles other than to tinker with springs.

Mike

I shall forever refer to the diff fluid check as the Fore-Play test.

[AustinAubinoe]

I heard that if you put synthetic in anything older then 1995 it will explode. Is this true?

[jeepguy77]

I heard that if you put synthetic in anything older then 1995 it will explode. Is this true?

It's definitely not true. The Dana 44 and 60axles have been in production since the 50s. They haven't changed anything major in them so why would it not be ok to use modern lubricants?

[carnuck]

Old seals sometimes will leak when they weren't with non-synthetic

[Mars]

I shall forever refer to the diff fluid check as the Fore-Play test.

Youre welcome

[jeepguy77]

Old seals sometimes will leak when they weren't with non-synthetic

I had this happen with the engine. When I put Mobil 1 in it.

[lindel]

It's interesting to hear that Currie doesn't like synthetic in their axles. Aren't they one of the leading axle manufactures for the offroad aftermarket?

Hearing stuff like that makes me wanna just keep what I have in there as it only has a couple thousand miles (but those are hard miles).

Seeing how Currie is the only manf I could find that specifically states NOT to use synthetics or they'll void your warranty, makes me really wonder what their issue is with it. Their claim is that it doesn't transfer heat away from the gears like a conventional oil does. I have a hard time buying that because where, exactly, is the heat going to go? The majority of the oil stays in the pumpkin most of the time.

If the heat transfer is that critical, why are the major OEM manf installing synthetics from the factory? Why do Dana and Meritor (big-rig axles) have no problem with synthetics?

I'd want to see how they're doing the tests, how hot do they thing too hot is, and what failures they're having.