Sorry, just not accurate!
There is nothing in synthetic base oils that will hurt seals.... and Viton is for diesel fuel.
But...synthetic oils ARE more likely to leak if there is a seal problem!
Less contaminants and not as likely to 'slug up' due to better thermal stability will allow synthetics to find a leak where dyno oils won't.

RJ

 

My Blackstone report was waiting for me when I got home tonite.
I sent samples of Engine oil, trans fluid and the rear diff AMSOIL which I drew when I put in the RP.

The only one that was good was the tranny.

This is what is written for the diff (AMSOIL 75-140):
Iron was the most out of line in this sample, and it's cautionary. Iron, along with nickel, show excess
wear at a steel part. We aren't sure where silver and titanium come from in this type of system but neither
should read at this level, if you compare to our averages The viscosity of the oil was low. No moisture or
excess insolubles were found. We see that you had this oil changed and we hope that helps bring wear
down to more acceptable levels next time.

 

That's why I like to use cheap oil and change it often. Some times you can find a deal on Mobil 1 but I haven't lately.
Billy

 

I used to do the same.
Guess I'm going back to that

 

just checked alldata and it shows new TSB

NUMBER: 03-003-06

GROUP: Axle

DATE: October 20, 2006

THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 03-001-04 REV. A, DATED MAY 11, 2004, WHICH SHOULD BE REMOVED FROM YOUR FILES. ALL REVISIONS ARE HIGHLIGHTED WITH **ASTERISKS** AND INCLUDE ADDITIONAL MODEL YEARS.
SUBJECT:
Axle Fluid Level

for our trucks (2500 and 3500)

either rear axle (8.25 or 9.25)
use 2.1L (72oz) 75w-140 synthetic

front axle (C205F)
use 1.6L (56oz) 75w-90 NON synthetic

both axles full level is 1/4" from bottom of the fill hole +(-) 1/4"

 

Steve, NONE of the 2500 or 3500 trucks have a 8.25 or 9.25 rear diff. They are 10.5 or 11.5. The front is a 9.25 ......

 

I have serviced many differentials in Dodge and GM trucks, and the factory fill definitely does smell like grapes. However I have not found any other brand of synthetic gear oil that shares this smell. So the only thing that this proves is that the OP no longer has the factory fill in his differential. It is quite possible that that dealer uses a different brand of synthetic for servicing. Even if they have been refilled with dyno gear oil, I would not consider it a big emergency to change it back to synthetic.

 

I serviced my rear diff@ 9000 K and it smelled like the bodies look like on CSI. Sour grapes would have been fine. I replaced w/Amsoil 75-90 Severe Gear and a Mag-Hytec cover. The front diff.@ 20,000K was like new.

 

you are correct...my bad when i read the TSB the vehicle info was below the chart and looked like it was for the 2500/3500 when it was actually for the dakota

the 2500/3500 is:

10.5 rear 1" from the bottom of the hole +(-) 1/4" use 2.5L (85oz) 75w-90 synthetic

11.5 rear 1/4" from bottom of the hole +(-) 1/4" use 4.1L(138oz) 75w-90 synthetic

9.25 front 1/4" from bottom of the hole +(-) 1/4" use 2.2L(76oz) 75w-90 synthetic