I was wondering exactly how to change the differential oil on a 78 280Z. I can see a plug that appears to be how to drain it but how do I refill it? How much do I use and does anyone have a particular type they would reccomend?

The filler plug is about 2" above the drain plug in the back of the housing.

Might be hidden be the mustache bar. You will have to crawl under and have a look.

Hint - loosen the filler plug before you remove the oil - if you cannot get at it and drain the oil - then :nervous:

Biker

It has an oil capacity of 1.3 Liters. (About 1 3/8 quarts.) But when it is installed in the car you wil not be able to get all of the old oil out, so it will take less than that to fill it back up. Just keep squeezing the bottle until it dribbles out of the fill plug hole.

I don't know if the R200 that came in the 280Z has this same problem, but on my 240Z the steel pipe plug is perpetually siezed in the aluminum rear cover. The last time I took the fill plug out I had to use a long open end wrench and a floor jack to generate enough torque to loosen the thing.

(Kids, don't try this at home...)

A tip to get as much old oil out as possible is do jack the front of the car up - worked for me.

I also used a hand held oil pump to actually get the oil back in the filler though, I found it quite tricky without.

use a 5 or 6 inch 1/2 inch extension (maybe it has to be a 3"), put this into a large 1/2" ratchet or breaker bar or torque wrench (long enough to go over the mustache bar, short enough to still fit and get leverage)....even put a pipe breaker bar on it for leverage...get a good 'catch' or grip on it (it you are being careless you can strip it)....and it will come out....sometimes you need 2 feet of breaker bar, but it will break free if done correctly....you are really only trying to 'break' the siezed action of the check plug...once it moves a little, it will be pretty easy to get out normally.

15 years ago I worked at Jiffy lube as a manager...I was always the guy to have to come downstairs and break these (but they were normally in a Nissan Pathfinder at the time)(that's the qualification for becoming a manager)....they always come out if done correctly...well I take that back...probably 1% are the kind that won't come out (but that 1% is normally due to stripping)....

Good luck!

Here's a picture of my differential. I can see the drain plug. It's at the bottom with the square indention. I'm not seeing where to refill it at unless it's that tube at the top? I need to jack the car up to get under it better but if not for refilling what is that tube for anyway?

Edited your picture.

I filled mine by removing the spare tyre from the well and removing the grommet that is in the front part of the well, when viewed standing at the rear of the car. I got a piece of clear plastic tube, largest diameter that will fit into the fill hole and placed it through the hole in the bottom of the well and routed it into the fill hole in the diff. Less than a metre of line was used.

Have someone pour the oil in through the top of the tube and you get under and watch for it to fill. It will run out when full. Replace plug and drive.

Im sure someone has filled their diff like this before.

Hope this helps out.

Regards

Joseph

OK the fill plug came loose easy. No problems there. I give up on the drain plug. How do I get that out? I don't have any square tools.

A long 1/2" breaker bar works well! As you may know, the square drive end of the breaker bar fits nicely into the drain plug. These plugs can be very tight and require some effort!

So if I got a socket wrench with a 1/2" drive that would work? Please forgive all my dumb questions. I'm still pretty new at working on cars, especially Z cars.

You could try it in the first instance but I wouldnt go forcing it if the plug is too tight, you may damage your socket drive.

Best bet is the breaker bar. Try impact blows with a lump hammer to loosen it.

Joseph