What type do I use to replace? whats recommended...whats "preferred".

Thanks

 

i use generic 80 w90 it works but i know alot of guys spend the bill on amsoil or royal purple

 

I used Lucas in mine when I fixed the leaking cover. Its still rolling so I guess its good. LOL

 

Book calls for 80-90 Gearlube, and may br best in your part of the country....if not towing heavy. I prefer 80-140. Also prefer Synthetic.....but that's a personal choice. If your plowing, I would do 80-140 in rear and front....just go easy till it has a chance to warm up a bit when cold out.

RJ

 

Do i need any additive or ? in either end?

Thanks

 

Royal Purple comes with the friction modifiers for the LSD type axels in it.

 

Yup... both, if what you get doesn't already have it.

RJ

 

80-90 is fine, use synthetic out back if you tow heavy. No additive needed unless your truck has an LSD - and some brands of gear lube already have it blended in. If you don't know which diff you have, you can tell by looking at the diff once you get the cover off. Only the rear diff would need additive in any case.

 

what would dictate LSD? what to look for when cover is off?

 

If you don't know what to look for....take VIN# to dealers parts dept. Ask for a factory "build sheet". Should be free and it will list all features and options that came from the factory!

RJ

 

An open diff is one cast piece with a big window and a cross shaft with two spider gears inside. The Powr-Lok is two pieces bolted together and has four spider gears inside. Pretty easy to tell.

 

I'm pretty sure an 01, 3500 won't have a Powr-Loc on his Dana 80........ but still a good description of an LSD!

RJ

 

He's also got an '89 W350 C&C with a dump bed.

 

Mine's a 91.5 D250. The build sheet is a sticker under the hood- Drivers side. says Limited slip diff. I read the owners manual and it pretty much says for any driving above -32F, you can use just about anything.

I did the royal purple from NAPA b/c it was easy to get and the additive for LSD. The additive is $6, so dino vs synthetic is only a few dollars. I think it was $11 quart vs $5 quart. Since it only takes a few quarts, it's not a big deal. Since diffs have sliding friction, I'd still recommend regular changes regardless of fluid type.




Michael

 

My money goes to amsoil, I've been using them for years and I'm very happy with it.

http://www.amsoil.com/scripts/runisa...msoiloaf:index