Diff Fluid

[Burner5509]

What brands and weight are yall using?

I see where Ford recommends synthetic fluid but I will not be using it. Currie enterprise did a test years ago on synthetic diff fluid vs dinosaur fluid and found the chunk to be be cooler on synthetic. That usually is a good thing, but they found out that the synthetic fluid did not take the heat away from the R&P like conventional oil did. Yes, I confirmed this with Currie after finding out.

[Doss]

That's nice and everything, but are you still under warranty? If you are, I'd run what Ford says to.

I'm running Mobil 1 syn in whatever weight the manual said to run.

Also, with a lot of things, any time someone did a test "years ago" on the current state of tech in a moving field, I throw that out the window (usually) if I'm applying it to today's tech. Another thing, if no one else did testing to support it (or even against it really), I'd be a little suspicious. That's my nature as an engineer and scientist. I'd have to know all the parameters, what the meaningful measurements are, and the test controls/conditions/etc..

[blackcloud2k]

I run royal purple in my diffs. Has friction modifier in it, and then I add just a tad more. Its a little pricey, but I have ran it in all of my trucks and jeeps over the years and have never had a failure.

[713Diesel]

I got the Amsoil that they recommended and their friction modifier. Not sure why but my fluid is getting REALLY DIRTY every 30-35k.

[Burner5509]

Originally Posted by Doss

That's nice and everything, but are you still under warranty? If you are, I'd run what Ford says to.

I'm running Mobil 1 syn in whatever weight the manual said to run.

Also, with a lot of things, any time someone did a test "years ago" on the current state of tech in a moving field, I throw that out the window (usually) if I'm applying it to today's tech. Another thing, if no one else did testing to support it (or even against it really), I'd be a little suspicious. That's my nature as an engineer and scientist. I'd have to know all the parameters, what the meaningful measurements are, and the test controls/conditions/etc..

Years ago doesn't mean 30 years really. Synthetic diff fluid and normal diff fluid hasn't changed over the years. The concept of how an axle works hasn't changed over the years either. Currie Enterprise is not a company I would argue with. If you know little about them they build and design axles, third members, suspension items, and on. The owner helps design things, and uses his own stuff to win rock crawling championships. Wheeling puts a greater shock load to an axle than driving down the road towing anything. The rear axle that comes on the Jeep (d44), so far i have rolled the stock splines, broke a chromoly shaft, and rolled the pinion splines some with only 35's. They an example of shock loading.

They did the test to find out why they were having to warranty axles so much. They found out that synthetic fluid does not pull heat away from the R&P causing failure. Just because Ford puts in the manual doesn't mean it's the best thing to use. For example, I have read where it recommended to use rad fluid other than Fords.

[Doss]

I know you weren't talking about a long time ago and I know who Currie is. I used to drag race a lot... they have good stuff and they have good offroad gear as well. I am also one of those that doesn't use Ford Gold (CAT for me).

That being said, I don't know how they conducted their test and how repeatable the results were... that wasn't my point. Going back to the warranty, regardless of what Currie says, if you tear your rear end up running dino when Ford specified syn, that's probably going to be on your dime just like if you run syn in a Currie rear end.

What you do with your truck is up to you.

[Burner5509]

Originally Posted by Doss

I know you weren't talking about a long time ago and I know who Currie is. I used to drag race a lot... they have good stuff and they have good offroad gear as well. I am also one of those that doesn't use Ford Gold (CAT for me).

That being said, I don't know how they conducted their test and how repeatable the results were... that wasn't my point. Going back to the warranty, regardless of what Currie says, if you tear your rear end up running dino when Ford specified syn, that's probably going to be on your dime just like if you run syn in a Currie rear end.

What you do with your truck is up to you.

Ok, I was making sure we are on the same page. Since both axles hold a decent bit I would rather use non synthetic due to the cost factor and the heat issue. I have the warranty until February (factory), but does that cover the axles at all?

[Doss]

3 yr/ 36k does and the 5 yr / 100k does (at least I'm pretty sure the 5 yr does).

I haven't heard of too many issues with the axles in the 6.4 going bad even with synthetic. That's just something to consider.