Taking care of the LS differential on a '88.
 

Hello, fellow "Ramsters".

Which kind of oil is recommended for year-round use; i live in Denmark where the temperature's commonly between +30 and -15 dgr. Celsius / +86 and +5 dgr. Fahrenheit.

The diff on my B250 is a 8 1/4" with LS, so i need an oil designed for this.

How to change the oil? It seems there's no drain plug, only a fill plug made of rubber.

How often should the oil be changed?

And, which type of LS is it? I've heard about clutch plate-types, and springs-and-gears types.

That's what i had to contribute with for now. :)

OEM gear oil for year-round use is SAE 80W-90 GL-5. Maintenance schedule I have says to check the level every 7,500 miles or 6 months. Replacing oil every 30K miles would seem (to me, at least) to be a very good idea.

You are right, there is no drain plug in your differential cover. I wish there was because it would make lube changes a lot easier.

I think the easiest way to change the lubricant is to use one of those vacuum devices with a tube to insert into the inspection hole (where the rubber plug is) and simply draw the old lube out. Before doing this bring the differential up to operating temp so the lube will flow out with less resistance.

You can remove the cover and allow the old lube to drain out but then you'll have to reseal the cover. Some guys use RTV alone to reseal the cover but I strongly recommend the use of a new cover gasket along with a thin coating of RTV on both sides of the gasket.

Refill capacity is 2.4 quarts US. For the LS diff you must add Chrysler Friction Modifier No. 4318060 or equivalent.

[Last month I replaced the GL-5 lube in my van with Mobil 1 LS 75W-140 100% Synthetic Gear Lubricant and everything is running fine. I believe the differential is running quieter than before but it could just be my imagination. :icon_screwy:]

* Note the Mobil 1 already contains a friction modifier for LS diffs.

If you decide to remove the cover you can take a look inside and see what type of LS diff you have, but for the record I think what you'll find is springs and gears.

Thanks for your help. :)