takovr

Just wondering how often do you all change the rear end oil?

STL94LT1

Unless you pull the diff, it will need to be pumped out.

c4cruiser

If the car is used for street or occasional "spirited" driving, then something like every 50K miles should be OK.

As mentioned, it will have to be pumped out (get a cheap fluid pump from Harbor Freight) and the new oil will need to be pumped back in. Some parts stores sell gear oil with a pump already in the bottle.

Use a good grade of 80W-90 GL5 gear oil and a couple bottles of the GM posi additive. Some people like brands like Royal Purple or Amsoil, but for the most part, there is not need for anything special. I would not use a synthetic in the diff.

pmihaltian

30,000 - 50,000 miles. Royal Purple gear oil works great and does not require the GM Positraction additive as it is already in the gear oil.

takovr

Thx all for the advice, also do I need the car on a "lift" or can I do
it without one.?

c4cruiser

I've done my 87 with the car up on jackstands. Best to take the RR wheel off.

Eakster

pmihaltian

I used ramps and this hand pump to extract the old oil and inject the new oil. (see attached write-up)

You can also get a kit for $80 which will allow you to drill and install a drain hole & plug on the lower portion of the differential. But even if you install the plug, you will need a way to inject the new oil into the differential. (see attached Word document).

pmihaltian

Should work great. Where did you purchase yours?

samsonb

I just pulled that pic from Autozone.com

But that thing is kinda small. Would probably be better to try and find a larger one.

Though, it would probably be a good idea to call the company first to see if it could pump gear oil. It just says an oil pump. So not sure what oil they are referring to.

dogfish246

Thanks for the writeup!

mtwoolford

oil can oiler worked for me...takes a while is all

BucfanTitan

Great article thank you very much for posting the PDF. I was wondering how to change the fluid. There is no drain plug like my truck has. I thought the whole cover needed to come off.

Thank you!!!!!

jake corvette

I use a garden sprayer to fill transmissions and final drives. Purchased it years ago from Tractor Supply for about ten bucks. Might be a couple of bucks more now.

Remove the spray nozzle, put the hypoid lube in it, pump it up a little and squeeze the handle. Works great. Way easier than a "thumb type" pump. Cost is not much more than a "bottle type" pump either.

Also use it to spray mineral spirits to clean areas that otherwise are inaccessible.

Clean it after each use to prevent deterioration to the plastic container. Better yet, get an older metal piece at a garage sale.

It's an excellent investment. Buy it now and it will last a lifetime - you'll thank yourself in the years ahead. LOL!.

MRPVette

Thinking about doing mine in my 95 this weekend so Royal purple 75W/90 and no additive needed ?

MRPVette

Or 80W-90 ?

JimLentz

So it seems.

http://www.royalpurpleconsumer.com/products/max-gear/

Max Gear is formulated with a friction modifier additive – no additional additives are necessary.

confab

I have read the bottom, center, diff bolt doubles as the drain. PO plugged mine with silicone, so I can't test. Had to pump it out with a mityvac.

Dakotaz

I use a big syringe with a hose attached that they use for horse injections.

Dakotaz

To add the oil I use a big syringe with a hose attached that they use for horse injections.