Question about Mopar 75w90 synthetic oil.

[Rosco]

I was at the dealer this morning picking up mud flaps and wheel well liners so I will have them on hand when my new truck arrives. Anyway, I figured I would grab two quarts of the 75w90 synthetic gear oil just in case the diff's were a little low (I would rather fill them my self). Well, the parts guy returns with the 75w140 synthetic thats recommended for use in the 2nd gens. I corrected him and said the factory fill for the third gen's was 75w90 SYNTHETIC. So off he goes into the back for about ten minutes and comes back with 75w90 gear oil, BUT it does not say "synthetic" anywhere on the container. I point this out and he states that his literature says the part number for this oil is a synthetic oil. I was not convinced so I did not purchase it figuring I would ask you guys. Does the Mopar 75w90 synthetic oil say SYNTHETIC anywhere on the container?

 

[Grayhackle]

Very LARGE letters on the label say SYNTHETIC, I just checked my bottle. I checked my rear and front diff after reading about the problems on this web site. I was low and went to the dealers and they gave me a quart for the back and a quart of dino for the front. Sort of a self service deal. It took the entire quart of synthetic and about half a quart for the front. I wouldn't buy it, I would wait and check it then raise heck with them for not properly servicing the truck. I am still wondering why they didn't pull the truck in and check it themselves!!

 

[Grayhackle]

Also, the parts tech said that the synthetic is $28/quart. Could this be right? The maintenance schedule says to change the front and rear differential every 15000 miles. Why, all of a sudden are we changing differential fluid, when previously it was one thing you didn't have to worry about?

 

[Rosco]

Grayhackle, thanks for the reply. My guess was the container would say SYNTHETIC thats why I passed on it.



However, I do have to wonder why your dealer gave you dino oil for the front axle because I thought both diffs had a synthetic fill from the factory. I could be wrong though and I sold my 2003 so I have no owners manual to refer to but if I were you I would double check.

 

[Grayhackle]

After your reply, I checked my owners manual and it does say synthetic, front and rear!! Hightailed it to @#$% Dealer and they checked in 2 or 3 places, various lube guides and concluded they have been screwing up! No telling how many DC 2500-3500 trucks are running around Tooele-Salt Lake City with Dino in their Synthetic. They are going to change it out tomorrow morning to all synthetic. I will save my paper work with a statement saying what the problem was or reason for service. Thanks for your comeback. I argued with them when they gave me the 2 different types of lube, their answer was that the rear end was limited slip and required different lube. Let this be a lesson to me---can't trust the @#$% Dealer!!



They know me so I didn't even have to stomp my foot or scream and yell this time!!!

 

[Tony T.]

I also have seen in the owners manual under schedule B to change differital fluids every 15,000 miles. I am assuming this would be for people that tow every day. I tow maybe 10 or 15 times a year, but schedule my maintenance under schedule B.