Differential fluid thoughts/recommendations...

Charlie D. wrote:
No comment on the extra mileage but synthetic was changed for synthetic.

Bingo.
Glad you got better mileage though.

No comment on the extra mileage but synthetic was changed for synthetic.

Sport45 wrote:

Jarlaxle wrote:

Sport45 wrote:
It seems to me that if shiny finned differential covers were the bee's knees for strength and longevity you'd see them on a lot of OTR tractors.

OTR tractor axles are running at considerably less than their design capacity than an axle on a heavily-loaded diesel dually. (Also note: I recall many OTR tractors don't HAVE differential covers: it's a dropout carrier, similar to a Ford 9".)

Yeah, I know. Just poking a little fun. In so many other aspects members here want to emulate big rigs. Seems like a flat black differential with a smooth back would be the way to do it. :)

As others have mentioned the shiny fins and extra capacity of aftermarket covers have not been proven to provide any additional service life. Some my find the dipstick handy, but I've never bothered to check my diff fluid level after filling it. If it's not leaking out (which is rather obvious) it's still in there. But hey, if they have the money to spend and it makes 'em feel better, more power to 'em.

Actually, painting it flat black WOULD help dissipate heat. (See, I DO remember something from HS science class.)

Grit dog wrote:

hawkeye-08 wrote:

jake2250 wrote:
I just changed the differential fluids and transfer case on my 2012 Silverado 2500HD.
I used Mobil 1 75-90 Full synthetic, I have 35000 on the clock and I gotta say that I am noticing a 1 to 1.5 MPG increase! Truck actually feels like it has less rolling resistance. I used Valvoline full synthetic in the transfer case..

How much did it take? I have a 2011 I am getting ready to do before towing this summer..

Jake 2250, you need to stay away from the 420!
I can guarantee the axle oil service netted you negligible mileage gain. Think about it. Going from pizza cutter hiway tires to bigger heavier mudders pulls 1-1.5mpg. Changing to a "better" gear lube may be good for .1-.15mpg.

Ha Ha puff puff pass,,Yeah I'm just calling it like I'm seeing it!!
Changed as i said, then took a road trip attended a class in Cold Springs Nevada with a stop in Truckee Ca, from Roseville Ca,,up and over the Sierra's and a good run up 395 out of Reno Nv. Bought the truck used (A year left over), I have not been getting over 10.8 mpg highway not towing. Did the service, made the trip (didn't spill the bong water), got 12.5 mpg to Nevada, coming home I averaged 12.8 mpg (mostly down the mountain) Hand calculation after fill up gave me 12.5 mpg on that tank of gas, Since then I have had two tanks come out at 12.1 mpg around town! Truck is all stock standard tires and a happy log!!
Have done All running gear service with Full Quality synthetics..
Guarantee all you want but something made a difference,, Maybe the lunar gravitational pull was high (huh huh high) that weekend? Maybe the Shell gas was over oxygenated? Maybe the UV index and low atmospheric pressure was in play,, heck I don't know,, if the Mobil 1 has higher lubricity than the GM factory fill then something is running better than before,, If I gotta change this stuff out every 10K to maintain better mpg's I will cause its working!!

I do what I do because I can. I just felt the locker rear end would like new juice.

chevman

Jarlaxle wrote:

Sport45 wrote:
It seems to me that if shiny finned differential covers were the bee's knees for strength and longevity you'd see them on a lot of OTR tractors.

OTR tractor axles are running at considerably less than their design capacity than an axle on a heavily-loaded diesel dually. (Also note: I recall many OTR tractors don't HAVE differential covers: it's a dropout carrier, similar to a Ford 9".)

Yeah, I know. Just poking a little fun. In so many other aspects members here want to emulate big rigs. Seems like a flat black differential with a smooth back would be the way to do it. :)

As others have mentioned the shiny fins and extra capacity of aftermarket covers have not been proven to provide any additional service life. Some my find the dipstick handy, but I've never bothered to check my diff fluid level after filling it. If it's not leaking out (which is rather obvious) it's still in there. But hey, if they have the money to spend and it makes 'em feel better, more power to 'em.

larry barnhart wrote:
We have 83K miles on our 05 3500 2wd and because I can I have changed the rear end fluid 6 times. over kill ya think?? Probably.

chevman

My current truck has 91k miles with the factory oil and my 05 had 170k miles on factory oil. No rear end problems or leaks.

Jarlaxle wrote:

Cummins12V98 wrote:

JustLabs wrote:

STEVEO496 wrote:

lawnspecialties wrote:
Is there any reason why switching to 75W-140 would not be advised versus 75W-90?

I'm not wondering if its necessary. Just if its not advisable.

75W-140 will hurt your fuel economy. At higher temps (towing heavy) the 75W-140 will offer more protection though.

A higher viscosity gear oil isn't necessarily better. There is potential for the differential to run hotter and be lubricated less.

75/110 is the preferred viscosity when towing heavy. 75/140 is too heavy.

Seriously? I'm not sure I have ever even seen 75W-110. My Cherokee, Magnum, and Dak called for 75W-140 if towing.

FWIW, my Crown Vic calls for 75W-140 in police or livery service, 75W-90 otherwise.

Yes "SERIOUSLY" !

If you read my previous post I did say the ECO DIESEL recommends the 75-140. The 2500/3500 contradicts saying one place 75-85 and another 75-90, I think the latter is what is recommended by Chrysler. AMZ/OIL recommends 75-110.

Jarlaxle wrote:

Cummins12V98 wrote:

JustLabs wrote:

STEVEO496 wrote:

lawnspecialties wrote:
Is there any reason why switching to 75W-140 would not be advised versus 75W-90?

I'm not wondering if its necessary. Just if its not advisable.

75W-140 will hurt your fuel economy. At higher temps (towing heavy) the 75W-140 will offer more protection though.

A higher viscosity gear oil isn't necessarily better. There is potential for the differential to run hotter and be lubricated less.

75/110 is the preferred viscosity when towing heavy. 75/140 is too heavy.

Seriously? I'm not sure I have ever even seen 75W-110. My Cherokee, Magnum, and Dak called for 75W-140 if towing.

FWIW, my Crown Vic calls for 75W-140 in police or livery service, 75W-90 otherwise.

It's an Amsoil product and recommendation, not OEM.

Sport45 wrote:
It seems to me that if shiny finned differential covers were the bee's knees for strength and longevity you'd see them on a lot of OTR tractors.

OTR tractor axles are running at considerably less than their design capacity than an axle on a heavily-loaded diesel dually. (Also note: I recall many OTR tractors don't HAVE differential covers: it's a dropout carrier, similar to a Ford 9".)