I have been changing oil/differential fluid in every vehicle I've owned but this one. Why? Because I keep reading about new and exciting ways to dork up your car and void a perfectly good warrantee. I can't take it any more!<br><br>I had been using my local dodge dealer for oil changes because they are cheaper than Walmart (hate that place anyway) and the quicky lube joints in the area. I still ended up paying 39-44 bucks per change though. Yesterday I asked my service manager how much changing the diff fluid would cost (without converting to synthetic) and he quoted me 100 bucks plus.<br><br>Anyone know why? I can get synthetic fluid (don't know exact quantity - I think 6 qts) and the LSD additive for 35 bucks or so at Autozone - and they reclaim my used fluids for free.<br><br>I've never had any problems (or induced any new ones) changing my oil or diff fluid. What does changing this rear end fluid (3.55 LSD for both vehicles) consist of (other than draining, adding the friction modifier, and filling to 1/4 inch or so of the filler boss)? I've heard some folks jack the axles up a bit to aid in draining - is this a good practice? <br><br>I stopped at NAPA, Autozone, and Oreilly's to purchase a simple service manual - (Clymer or Haynes) and cant find a 2002 addition. Are there any major differences (in the servicing arena) I need to be aware of if I purchase the 2001 addition?

 

[quote author=AFSMSgt link=board=4;threadid=9793;start=0#93533 date=1042918448]<br>I've heard some folks jack the axles up a bit to aid in draining - is this a good practice? <br>[/quote]<br><br>Yes.<br>Drain the Differential, then jack up each side, 1 at a time, to get the oil out of the axles.<br><br>Then when you fill it, fill it to the drain plug, the drive it around for a couple blocks or so to let the axles fill back up, then check the level and fill to appropriate.<br><br>As far as the LS additive, etc I'm not sure, I'll let someone else chime in on those.<br><br>phox

 

Some synthetics claim friction modifier additive is not necessary. I didn't need it with mine, but some people have reported that they had to add some to synthetic to stop chatter. Too much additive will render the LSD useless, or not effective. I'd see how it is first w/o modifier, then get some if needed. It is recommended to drive eight to ten tight figure of 8 patterns after changing LSD fluid to get the new stuff worked in.<br><br>The Dana 80 holds 5.05 quarts. I think that .05 equates to like 1.6 oz. I used the orange RTV high temp silicone for the new gasket on mine. Good luck.

 

I changed mine at around 10K, and went with Mobil 1. I think I paid around 7 bucks a quart, but I don't remember exactly. Mine definately required LS additive despite what it said on the bottle, as it hopped like crazy. I used 1 bottle of Kendall, and that seemed to stop most of it although I sense a little bit on cold mornings.

 

Amsoil in my previous '99. No modifier needed. Just received M/Hytec, and picked up Amsoil for my current truck. Installing this week. No modifier unless necessary.

 

Don't forget to fill in the stamped numbers on the diff housing with a little RTV before installing the new cover.<br><br>-Tom-

 

If you are towing, DC recommends a synthetic in the rear. I use Royal Purple in my diffs and did not need any friction modifier. With the stock covers, I used the permatex ultra black and like commatoze said, don't forget to fill in the stamped numbers! The Mag-Hytec covers have a built in O-ring and drainplug for easy service w/out removing the cover! You may want to consider these in the future!

Tony

ps -- as far as service manuals, get the best: http://www.techauthority.com

 

Since I don't want to spend hours &quot;stoning the differential nesting surface&quot;, I intend to use a little Ultra Black here and there. We buy it by the caulking gun tube ;D<br>M/Hytec is a cool product, but it's a good idea to pop the cover once in a while to have a real look-see. That makes it easier to get the big chunks out

 

The surface of the housing is machined nicely, it's those stamped numbers you have to watch out for. I used a single edge razor blade to scrape the surface free of RTV. Then I did what you suggested, filled in any dings with a little RTV. I used no other sealant, and the o ring has sealed fine. BTW, there's a nice big magnet in the OEM cover so hopefully they'll be no chunks in yours. It's just that reeking gear oil! ;D

 

Sorry, the &quot;stoning&quot; crack was a bit of an inside joke, and I could not help myself

I love the smell of gear oil in the morning!

;D ;D ;D

 

[quote author=BigK link=board=4;threadid=9793;start=0#94137 date=1043087224]<br>......I love the smell of gear oil in the morning!....<br><br>[/quote]<br><br>The test of your love will come when you crack open the bottle of ant-slip additive. ;D I smelled mine thru the plastic bottle. ;D

 

LOL

With luck, I won't need it. We'll see ???

 

I can't find any local parts stores that stock differential gaskets (using 2002 dodge ram 3/4 ton, diesel limited slip on their computers). I believe I have a Dana 80 (owners manual mentions a 70 too) - how do you tell the difference?

 

You will more than likely not find a gasket. I used the red hi-temp RTV on my 95 the last time I changed it. Put it on the cover and the rear end, left it tack up a little, put the cover on finger tight and left it set over night. Tightend it up the next day and filler it up. No leaks at all.

 

The rear end should be listed on the line sheet under the hood.