Diff change intervals with Synthic oil

[BillDriscoll]

Using Royal Purple 75w-140. Have 49K on the diffs and 41K on the transfer case. Gonna do the ransfer case right now with atf+4, but are the diffs due if im using the RP syntec at 49K miles? I'm guessing time to do them too!!

thanks

Bill

 

[HBarlow]

The owners manual for AAM axles calls for 15 that's one five thousand mile change intervals. I used 50k on my '06 for 230k miles and my '08 which so far has 107k miles. I use a Mag-Hytec cover and ignore the 15k requirement.

 

[Wingate]

The owners manual for AAM axles calls for 15 that's one five thousand mile change intervals. I used 50k on my '06 for 230k miles and my '08 which so far has 107k miles. I use a Mag-Hytec cover and ignore the 15k requirement.

same here. . I changed the factory stuff out at about 10K and installed Mag-Hytec covers and Valvoline oil. Have no plans to change it again until about 100k or so...

 

[RonD]

I changed mine at 5000 miles with 75/90 Mobil #1, then at 30000, then at 90000, and then they stay at 60000 intervals, I will do the same when I get my 2012 in a few weeks, I question the reason for 140 weight gear lube.

 

[Wingate]

Im sure everybody has their own reasons. . i run the 140 for peace of mind... with 110* days for the last couple of months, very little to no winter to be concerned about... . I like the comfort feeling I get from putting 140 in it. My truck really does not see much in the way of "grocery getting" running unloaded down the highway... For the most part, if it hits the road, its got something hooked to the back of it...

 

[NavyDood]

I am using Amsoil synthetic 75w-90 and have the factory cover. I just towed 20K combined from MD to TX going the northern route through IN averaging 65mph. When I got further south into AR and TX, the outside temps reached 106°F. When I checked the temp of the differential with my infrared gun in AR for fuel and in TX for a pit stop the highest temp I saw on the dif cover was 184°F.

There's no reason to run anything greater than 75w-90 unless you are towing heavy in Death Valley temps on a daily basis. That is right from AAM's mouth. If you use a true synthetic, you won't have to change the fluid for at least 50,000 miles (heavy/consistent towing). My last change dif fluid change had 100,000 miles on the lube. 95% of that driving was commuting.

Here are some pics on my last fluid change with 100,000 miles on the fluid.

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[steved]

I think one of the reasons for the "shorter" OCI on the AAM differentials is the LSD, and how it supposedly doesn't like dirt (even the "dirt" it generates from use).



With that said, I have ran RP 85w140 for over 100k (over 200k on the truck) and currently run Schaeffers 75w140. My fill of RP 85w140 looked just like the day it was installed and there was almost no fuzz on the neodymium magnets I installed. Had I known this (curiosity caused me to do the drain/fill), I would not have changed it. This fill of Schaeffer is still crystal clear after about 35k miles. My driving style is mostly highway, but some 10k GVW trailer towing and I do run it fairly hard through the gears.



I do not buy the 15k OCI for the AAM, which is absolutely no different in design than the previous Dana axles or even the AAM built the previous 30 years. The only thing that's different is the LSD, and that only applies to those of us with LSD-equipped trucks.



The best part is that the GM 11. 5AAM (same axle under a different truck) has either a 50k OCI or no OCI, depending on the model year. Why are the OCIs different for the same axle?

 

[NavyDood]

I do not buy the 15k OCI for the AAM, which is absolutely no different in design than the previous Dana axles or even the AAM built the previous 30 years. The only thing that's different is the LSD, and that only applies to those of us with LSD-equipped trucks.

The best part is that the GM 11. 5AAM (same axle under a different truck) has either a 50k OCI or no OCI, depending on the model year. Why are the OCIs different for the same axle?

Because Dodge just wants us to buy their mediocre Mopar dif fluid for $30-$35 a quart. :-laf

 

[amsoilman]

The Amsoil recommendation for (SVG) "Severe Gear 75W-90 is 100,000 miles of service or according to OEM manual, whichever is longer. (NORMAL SERVICE)

50,000 miles of service or according to OEM manual, whichever is longer. (SEVERE SERVICE)

ALL pulling is SEVERE SERVICE.

 

[Wingate]

The best part is that the GM 11. 5AAM (same axle under a different truck) has either a 50k OCI or no OCI, depending on the model year. Why are the OCIs different for the same axle?

So that the local dealership can use scare tactics to brow beat the un-informed into paying for a differential service, transfer case service, battery maintenance service, windshield washer service, blinker fluid service, and routine brake inspection at 15K miles!!!. .

 

[RDeFayette]

Don't forget that the front and rear diffs come with 75W90 synthetic to begin with.

I always change at 50k and have never had any problems.

If at anytime the truck is operated in water that has even a remote possibility of getting into the axle vent it is imperative that the fluid be changed ASAP.

Running a hot truck through cold water makes the air inside the diff contract thereby drawing water into the diff and contaminating the gear oil. Oil and water don't mix! If you have ever drained the gear oil and it looks like a Yoo-Hoo it has water in it.

just my $0. 02, and you can forget about the so called one way vents too.

 

[ColemanR]

So at what point does a person say its time to rebuild a rearend I'm getting parinoid I change it at around 50k and am currently at 470k+ the plug is clean I have less on the plug than pic above just curious Im thinking its time but all looks good.

 

[HBarlow]

I don't think anyone on TDR has ever reported wearing one out. I know of several Dana axles with close to a million miles on them with an original rear differential.

 

[steved]

So at what point does a person say its time to rebuild a rearend I'm getting parinoid I change it at around 50k and am currently at 470k+ the plug is clean I have less on the plug than pic above just curious Im thinking its time but all looks good.

As long as the magnet stays fairly clean, I wouldn't worry about it... that's probably your best indicator for wear inside the differential. Keep doing what you're doing, it seems to be working well for you. My magnet was practically clean with 100k on the oil (truck at around 220k)... once they get broke in, they don't shed much.



And they do typically give some warning signs well before they leave you sitting along side the road.