I am considering these two oils to put in my front and rear differentials on my next swap. I am going to leave it in until 100K (55K miles). I don't find much wear material at all when I change the diffs, and the fluid looks good, so I think it is ridiculous to keep throwing good money away on needless gear oil changes, especially when I have it broke in well. The company I work for between farming seasons has a fleet of about 55 2500 and 3500 Ford and Chevy trucks that go for 200K miles (about half of the miles are towing fairly heavy) in 4 years with no differential fluid changes EVER and have virtually no problems. (My 04 Chevy company truck has 102,000 on it) I would hope my Dodge can make it 55K on the best gear oils known to man!

I just wanted to know if anyone had specific problems with either oil, and what they were. Since this truck is nearly always hooked to a 24' livestock trailer, I am going to go 75w-140. I would like to use Schaeffer's Syn, but don't want to buy a 5 gallon bucket of it, and I wouldn't have enough left over to properly service any of the tractors anyways. Thanks.

 

Both are good oils. Pick one that's easiest to acquire.
BTW, I'm running Royal Purple 75w-140 in mine.

MikeyB

 

I'd run the Redline shockproof Heavy.

I'd personally go at least 50K on a diff change with this fluid. Maybe less if heavy towing is a factor.

For heavily-loaded diffs, the Shockproof is the best going. But it's a pain to clean up! It's sticks to EVERYTHING, like it's axle grease or assembly lube or something. The pinkish-purple color is interesting too, and clearly an indicator of a superior product. (though purple would obviously be really close)



BTW-- I've used both the Redline and RP product with exceptional success. I favor Redline for diff and gear oils, RP for ATFs and engine oil. But there's no wrong decision here.

 

I used to run my 97 like I stole it. All day interstate trips as hard as that mother could pull my 5er with 800+ torque! I ended up with RP 85w140 before I stopped getting metal on the magnet. No 75w90 could do the job. I thought about Redline but couldn't find a dealer anywhere close. I think you're on the right track using at least 75w140 syn. I used RP 75w140 for a short time and then I check the vis. indexes. There's a big jump going from 75w140 to 85w140. Almost as big as going from 75w90 to 75w140. The 75w140 seemed to be doing a good job but I wanted more safety factor with what I was doing with my truck. Guys on these forums said... no no no, you can't do that - the pinion bearings won't get lubed in cold weather with 85w140. Yeh right - I think no metal on the magnet (and running a little cooler) proved them wrong. I ran 24k on the last 85w140 and the analysis was great - anything else I ran long enough was trashed at 12K. Craig

FWIW - I put bearings in my Dana 80 at 48k and coated them with RP 85w140. I had to remove them a couple of times to adjust the shims. I used oxy/acetylene to heat the cones til they would fall freely onto the pinion and the carrier and didn't burn off or even discolor the lube.

 

I've got some Redline 75W90NS to put in mine when I get the time. I don't tow that heavy (~6000lbs) and only once or twice a month right now, so I didn't think a heavier oil was necessary for me.

 

I guess my other question now is since we don't need a friction modifier additive in our differentials to make them lock up, will it still help with wear to have the additive in there anyways? I see Redline makes this statement regarding their friction modifier add: "this product will significantly reduce the friction break-in of differentials, reducing break-in temps for as much as 50 degrees F.....add only enough to eliminate the chatter and avoid making the plates or clutches too slippery. "

So it makes the oil more slippery--wouldn't that be a GOOD thing, even if we don't necessarily need it for function of the anti-spin mechanism? Or is it better to not have the additive, which dilutes some of the EP properties of the base fluid & additives?

 

I've always heard the LS additive is only to be used as much as necessary in LS diffs. These days the lube mfgrs. don't want anything else added. I've always wondered about the miracle EP additives I always see at the RV shows. I think there is a trick with those wear test demonstrations but don't know what it is. I think if those additives really worked so great they would be more popular. Craig

 

I ran normal pennzoil in my back diff for 60k miles and when I pulled it out it looked good. It was a darker golden brown. I was impressed cause when I pulled the stock fluid out at 40k it was really thin and black. The front diff I just changed with 102k miles on it and it looked brand new but had a little water in it from fourwheeling. I put synthetic fluid in both.

 

Well I emailed Red Line and asked them what they thought:

Request Type : Technical Request
Message : I own a 2004 Dodge Ram 2500 with the Cummins in it which nearly is always hooked to a heavily loaded trailer. The time to change gear oil out is coming up, and I am wanting to run Redline--Dodge specs 75w-90 (normal use) or 75w-140(frequent trailer towing) It also will see an ambient temperature range of -15f to 100f+ here in Illinois. This truck has the "anti-spin" rear end but it is of a different kind that does not require the addition of any friction modifiers, etc. Just wondering what gear oil you would recommend for my application. Thanks.


Matt,

Thank you for contacting Red Line Oil, in your Dodge Ram used primarily towing I would recommend the 75W140. It would be well suited for your use and range of temperatures. The 75W140 contains a friction modifier, though not needed for the limited slip is beneficial for friction and temperature reduction.

Regards, Dave
Red Line Oil

 

Another question, anyone know how many times the fluid can be changed before you need to replace the reuseable gasket on the newer model trucks?

 

On the Dana 80 on my 2001.5 there is no Gasket just RTV

 

as long as you dont tear it should last as long as you have the truck

 

The gasket will last a lot longer if we stop with the ridiculous 15K Gear Oil Swaps....

(I hope I am not eating crow when my diff fails because I ran Red Line, Royal Purple, Amsoil, or Specialty Formulations for 55K....)

 

Keep the 15k drain intervals for warranty reasons. After the warranty go for the extended drains.

MikeyB

 

What is Fluid capicity on the front and rear diffs? Just wondering how many qts you need.