I am planning on a diff. service soon. My truck has the 7/70 powertrain warranty. Should I use the Mopar syn. fluid and addative? If I don't, do I chance voiding the warranty?
It was serviced once by the dealer (no charge) about 25k miles ago.
Next, is it better to take the diff. cover off to drain or use pump to extract the fluid. I would suspect that the pump will not get ALL the fluid out.
What is a good syn. diff. fluid and addative?
How many qts of fluid will it take?
Sorry for all the questions.
Dealer quoted me $129 for the service.

 

Check this site out: http://amsoil2.cpinternet.com/script...msoiloaf:index

Just type in your vehicle and you should find the spec's..

OH BTW, research AMSOIL Series 2000 75-90 synthetic, without the additive...
OR Gear Lube 75-90w with the additive. Depends on which rear end you have...
I ordered the 2000 yesterday - 8 qts - $57.60, doing frt and rear ends (4x4). I think the SAE 75-90 Synthetic Gear Lube is 5.85 a quart, with Preferred Customer option.
Good Luck

 

I'd use the MOPAR additive; it seems to work the best. For fluid I used Mobil1. My LS rear needed the additive despite what it said on the bottle. They want a lot of money for such a simple service that you can do on a Saturday morning! As far as cover removal or not. There is a large magnet on the stock cover that collects metallic mud, but it's best to pull the cover I think. I also preferred the MOPAR gasket maker for this task. I think it worked better than Permatex. I used an old fillet knife and tapped it into the edge of the gasket with a mallet to separate the cover from the housing.

 

I changed mine at 114,000. The lube that was in it was clear. Had no particals
running over the gear case edge nor did I find any with a small magnet. I thought it needed changing? Guess it could have gone another 50k if it had not been for the leaking axle seal on the left rear.

Dave

 

When I changed mine I had 30,000 miles on the truck the oil wasnt in great shape but OK. I pulled the cover and really cleaned out all the old oil by jacking up one side at a time letting all the oil drain. I filled it with Valvoline 80-90w and two bottles of Mopar friction modifier. Everything works great. I didnt use synthetic for cost reasons and I didnt think I'm in cold enough of temps to justify the extra cost.

 

IT IS EASY TO SAY GO WITH THE REGULAR DOPE BECAUSE IT IS CHEAPER, BUT IN REALITY THE SYNTHETICS LAST MUCH LONGER. IF IT COME WITH SYNTHETIC, PUT SYNTHETIC BACK IN. DON'T PAY SOME DEALER AN HOUR'S LABOR FOR SOMETHING YOU CAN DO IN 15 MINUTES. I USUALLY HOLD A RAG OVER THE FILL HOLE & FILL IT UNTIL IT'S POURING OUT, & QUICKLY PLUG IT. WAIT 15 MINUTES & CHECK IT AGAIN. TIGHTEN UP & RIDE ON!

 

I use Amsoil 75w-140, and it did not need the friction modifier for the LSD.

I went with the 75w-140 because the manual says if you tow frequently, that is what they recommend. Is it necessary? I doubt it, but oh well.

I have 80,000 miles and have changed it several times now.