2nd Gen Non-Engine/Transmission Dana 80 Oil Analysis

[jrobinson2]

If anyone thinks gear oil doesn't need to be changed if you don't tow this should change your mind!

Miles on truck 78808, miles on oil 78808 less than 10000 miles towing/ hauling, (probably less than 5000) Truck gets stomped a bit when I drive but mostly easy highway miles to town with the wife driving.



Dana 80 rear with limited slip.

wear metals PPM

copper 4 (N)

iron 881 (S) (my test shows normal as up to 200)

chromium 21 (N)

aluminum 6 (N)

lead 1 (N)

contaminants

water %. 0

silicon 166 (S) (my test shows normal as up to 40)

I don't understand the high silicon, how does dirt get in there? Could it be casting sand still in there?

Has anyone sampled differential oil at low miles and was silicon high?

Does any one have any numbers to compare these to?

How often do you change gear oil with little towing?

The iron # has me a little worried but there's no noise or excessive heat as far as I can tell, maybe just to many miles on the oil. I refilled with a full synthetic, I think I'll pull a sample in 10000 miles to see what it looks like.

Jared

 

[John Berger]

Good supporting evidence for 30K interval changes. I went 38K with Amsoil's Series 2K 75W-90. The oil analysis was good, but Blackstone recommended I not run it any further. The factory stuff is nowhere as good as Amsoil or any of the other popular lubes. Your high iron count is probably normal with that many miles. I've seen high (275 ppm) readings from my transmission lube. I did the sample after 12K on the lube of which half or more was towing heavy. You are probably OK. I would follow your advice and do a sample soon. Run it 5K and do the sample. It's not that expensive. You might want to consider a Mag-Hytec if you got the funds available. Doubles the capacity and makes maintenance easy.

 

[illflem]

While I agree on changing the differential fluid at least every 50k I don't think your analysis numbers mean much since it was the first time it was done.

Most of the high numbers recorded can probably be attributed to manufacturing debris and break-in wear.

 

[Rammin On]

Your high silicon # is most likely coming from excess sealer used when the cover was installed ... .

 

[amsoilman]

I can give you some numbers for comparison.

94"Dodge/Cummins 3/4 ton 4X4.

128,00 miles on truck

69,000 miles on rear differential gear lube, using Amsoil series 2000 75W-90.



Visc@100C 15. 2 cSt

Oxidation % 4. 4

TAN 2. 3

(Fe) Iron 169 ppm

(Cr) Chromium 1 ppm

(Pb) Lead 1 ppm

(Cu) Copper 1 ppm

(Al) Aluminum 2 ppm

(Ni) Nickel 2 ppm

(Mn) Magnesium 4 ppm (Additive)

(Si) Silicon 28 ppm

(B) Boron 178 ppm (Additive)

(Ca) Calcium 24 (Additive)

(P) Phosphorus 1213 (Additive

(Zn) Zinc 32 ppm (Additive)





Remarks: No Corrective Action Required. Oil is suitable for continued use, Resample at next regular interval!



Hope this helps you.





Wayne

amsoilman

 

[waterdonkey]

I second what Rammin On said about the silicon. My first oil analysis on the motor came back with high silicon. The lab stated it was probably gaskets or sealing material. My second analysis came back good.

 

[C Schomer]

10000 miles of towing alone is enough to ruin the OEM lube. My OEM junk was coal black and stunk (burnt) to high heaven at 9k with stock power - about 7k of that was towing. I tried Ams 2k 75w90 for 13k - it looked nearly like new but I developed ring and pinion noises. I then tried RP 75w90 for 10k (noises went away) and started doing analysis- the RP looked like new but the report said it was high acid and low visc. I'm sure the Ams 2k 75w90 is good stuff but I ran it too long. Shortly after that, it needed pinion and carrier bearings. I got a Mag cover just for the extra oil capacity and switched to RP 75w140. I learned the hard way about using a 90 grade in these monsters. I guess I still thought 140 was just for F-20 tractor rear ends. Hopefully it will hold up better now. D/C says change at 12k when towing for a reason. Even if it looks good, there's a good chance it will be trashed! Craig

 

[jrobinson2]

John Berger

MagHitec was on my "short list" but was replaced (among other things) by a $730. 00 steering knuckle, maybe next time though. My samples are free so I'll pull one soon.



illflem

I think 50k is about right, my '76 Dodge is at 350k with no problems on 2 changes but I plan on a lot more than that from this truck



Rammin On and waterdonkey

Now that I think about it my brothers Durango had high silicon on the first engine oil change, I bet your right.



amsoilman

That's what I was looking for, a clean sample to compare with! It helps put mine in perspective.



C Schomer

I don't tow much, a car trailer or 4 place stock trailer every few months and a 3000lb camper a few times a year. The oil wasn't burned at all, it looked quite nice compared to some I've seen. I bet your rear had a problem from day one, I know a couple of guys that run 18 to 25k lbs all the time and just look at me funny when I ask about changing gear oil



Thanks for the info

Jared

 

[Sled Puller]

This summer, I was changing my diff lube once a week, a few hundred feet at a time!!!:{

 

[Gary - K7GLD]

The limited-slip clutches used in most of our differentials is an abrasive - has to be in order to "grip" properly and do its intended job. Normal operation, turning, small circumferential differences in tires, differing road surfaces, all cause those clutches to wear and shed varying percentages of their facings. THEN what we have in our differential lube, is an abrasive in suspension being circulated all over various gears and bearings...



NOW, *if* you use some brand/type differential lube that remains pristine, clear and pure over long intervals, *I* would almost GUARANTEE you that you ALSO have a LS unit that is pretty much non-functional! ALL *normally functioning* clutch surfaces WILL create wear - the ones in manual transmission vehicles do, the ones used in auto trannies do - and so should the ones used in LS rearends - IF they are doing the job they were designed for!



And THAT is why we should change our differential lubes FAR more frequently than we do manual transmission lubes. And if *I* had a differential lube that stayed clear for many tens of thousands of miles, I would be a little suspicious as to the efficiency of my LS operation...

 

[Sled Puller]

That certainly sounds sensible, gary, but was not true in my case.



Before I pulled heavy at the track, I would run one year, 30,000 miles, and drain the lube. It was great shape, and the LS worked fine.



I saved the lube and put in Dads Chevy! LOL.

 

[JJW_ND]

Here is my .02

My first oil test with 28K on factory oil came back 945Fe and 461Si. Second with another 50K came back better on wear metals with 199 FE and 154 Si but TAN was getting up their at 6. 7. This was with Amsoil regular 75W90 (Series 2K not out yet). Third interval change and sample was 35K later. Fe was 243 Si 88 and TAN down at 2. 3 (all fine for continued use). Forth interval was 31K later. (Running Series 2K 75W90 now). Fe was 57, Si 58 and TAN 2. 8, ran oil another 12k and changed. Last sample was 40K later (206k Total Miles) with similar good results at 92 Fe, 32 Si, and 4. 2 TAN.



Up until this point the truck was pulled hard (especailly how it would wear rear rubber). Every differentail service included 2 full bottles of Mopar LSD additive.



I would change the factory oil at the second or third oil service. Lots of break in wear metals. I would change the next at 30K or less. After that One could stretch out to 50K. When I had my driveline rebuilt at 210K, the driveline shop comment on how quiet the rear diff is. It is all factory original!



I can also say the LSD acts like like it is welded solid when spinning or pusing the traction. Yet it does not bark or jerk around corners. Best LSD I have driven. I have said this before, the older middle 90s seemed to have a more aggressive LSD then the lat 90s and early 2000s.



jjw

ND

 

[illflem]

Should LS differential fluid be changed more often than a non?

 

[Loren]

Silcon (sand) is different from silicone (rubber).



Silicone sealer is what we use to seal the differential cover.



Silicon is what glass and computer chips are made of.



High silicon numbers will not result from an excessive amount of silicone.



Loren