My GSL SE has oil dripping from the rear differential
 

I've started to notice when I park, my rear differential drops a couple of drops of oil. Its right under the LSD and doesn't seem like a lot but I want to know if it is a problem.

This is the underside of my car. Also, does anyone see anything bad there? Is anything look terrible?

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I would think its probably leaking at the front where the driveshaft meets the diff. Theres a seal
there, like an axle seal that could be the culprit. I would just check the level and make sure its
good on a regular basis. Don't forget the LSD treatment stuff as well. Might want to completely
drain it and change it out. Might help.

when the pinion seal fails it slings oil up and to the sides too. i don't see oil on the exhaust or undercarriage.

i think it's a leaky diff drain plug. teflon tape it.

Hard to tell by the pictures either DriveFast or t_g could be right. If you can grab a picture from the side (in front of the rear wheels looking back towards the rear end and with some better lighting if possible).

Had a very similar issue and it turned out to be a poorly fitted drain plug on the differential. But to be sure, take another pic as Jsieve said, from the front of the diff in order to rule out seal failure.

Yeah. I'll go take a picture right now and post it.

Here is the diff from the front. It doesn't look like its coming from where the driveshaft connects with the diff. It looks like its coming from the bottom.

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Heres the amount of oil or whatever thats leaking. Its not alot but it does worry me a little.

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I went and powerwashed the diff at a self service car wash to clear the view a little bit so I could try and pinpoint where the oil leak is coming from. I don't think its coming from the bottom bolt opening. (But its still possible thats where the leak is coming from) My dad says there is a gasket around the outer edge of the diff and thats almost where I think the leak is coming from

Sorry, It's really difficult for me to get a good picture of the diff. (Im 6 feet tall)

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Based on the height of the residue around where the differential bolts to the housing, it looks like it's leaking from that seal. The drain plug may be part of the leak. Since you cleaned off most of the residue, check it regularly over the next couple trips to see if you can pin point where it's coming from.

Honestly unless you've already done it yourself and given the age of our cars it might just be a good idea to pull the lsd out and clean it by hand with some fine grit sand paper if you wanna make it shine (I'm personally a paint guy, I'd go respeed blue), then pull it apart and replace the seals and give it some new fluid. Sounds like work I know but it's a nice piece of mind, and when it's apart you can grab some pics of the internals and maybe search around to see how long it'll be till you need a rebuild.

Wow! I'm just truly impressed by the underside of your car! Almost no rust and you even still have the exhaust shields in place. Looking good for a 30 year old car.

Yeah, I got really lucky finding this car. Two owner and the guy bought it in '89 and has only put 30k miles since then. Its got 89k right now. :D

I think I've found where the leak is. I think its a seal on the front of the diff. Not where the driveshaft connects but around the outer edge because the drip shows the path it came from. I'll take a picture later after I come back home and I'll make a red circle around the area where I think its coming from. Thanks to all of you for helping. Its really appreciated.

Thanks for bringing this up.
I just noticed I have some oil on mine, but so far it looks like the drain and fill plugs.
Not leaking enough to actually drip to the ground, but worth further investigation.

Here is the latest picture. I've drawn in red the area where I think the oil is coming from. and the arrow at the bottom shows the path it travels to where it falls to the ground.

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Thats the area where the pieces of metal come together. Is it a seal? If so, can anyone link me to a guide on how to fix that? and should I pull the LSD and do a cleaning and rebuild it to make sure its still good?

I had a leak in my old FC back in the day and ended up burning it out leaving me stranded on the highway.

You definitely need to pull the pumpkin, clean it, reseal, and refill. If it is in the budget, may I suggest a internal upgrade? A bit pricy but the I have been happy with the OS Giken unit intended for a Miata.

So I just took it to a oil change center and they let me in their pit to have a look at it and check my fluid levels. It just looks like I'll have to drain the fluid in the diff and disconnect the driveshaft and replace the seat. Also, the guy noticed that my bushing (connected the control arm) was broken, nothing big but it was just broken. And that my skid plate for my exhaust is bottoming out on the entrance to garage. Can anyone link me to something that could help me with any of those problems? Apart from the suspension problems which I'm already planning on ordering the Racing Beat full suspension kit.

Since there is oil leaking up high, it's not just the drain plug. You need to pull the pumpkin and reseal it. You have to pull the axles out to get the pumpkin out. Use a good sealant like RTV Ultra Black or Permatex® Gear Oil RTV Gasket Maker.

I have to remove the entire axle? I ordered the front seal for the differential so I thought all I would have to remove was the front of the diff. Can you link me to a guide on how to remove the axle? Because I can't seem to find something showing the exact thing I'm going to have to do.

There is a guide in the archives about this process. Its not too bad from the looks of it.

Of course, he means 'both axles', as there are 2 - one coming in from each side!

This isn't a difficult job by any means, but does tend to get messy, since you have to drain as much of the rear diff oil as you can to get the pumpkin out. Also, be VERY sure that when you refill the rear diff that you add the GM LSD fluid in the prescribed amount - no more, no less.

Without the proper GM-specific LSD fluid mixed into the gear oil, the plates won't engage properly, will overheat and lose their temper and then they'll fail. The correct additive is linked here for your convenience, and so you don't forego doing it:
As a sidenote, everything else under your -SE looks great from the pictures you've posted. Get the rear diff taken care of and it should last you a good long while. I last changed the rear diff fluid and GM LSD additive on my -SE back at 145k miles and it's been good for the last 80k.

Keep it on the road!

I would clean it up and just torque the bolts a bit and see if tightening it up helps stem the flow
first.

The problem I have is that I don't own any good tools to do this. I've only got a basic tool set of wrenches. I'd have to buy some jack stands or ramps to allow myself to get under the car because it's hard to get under. Do I really need to do this or should I be fine with leaving it and just tightening the bolt and seeing if that stops the leak. (but i've already ordered a new seal for the front of the differential.) Could I just drain the oil in the diff and replace the seal and forget about it or take it all out and do a refurbish?

First of all the seal at the front of the diff is not where it is leaking. It is where the diff mounts to the housing, judging from the pics you posted.

You can fix this using only basic tools. The only challenging part is removing the axles from the housing. You have to pull them out to remove the diff from the housing. The axles usually are kind of stuck in the housing and you have to figure out how to get them to come out. You can use a big slide hammer, or go youtube and get suggestions on how to get them out, there are lots of creative ways to do it. I use a 10 foot logging chain bolted to the hub with one of the lug bolts and standing about 6 feet from the car whip the chain. I know it sounds odd, but it will snatch it right out. pull the diff, clean the mounting surface and put some silicone sealant on it and bolt it back in. problem solved. no special tools needed, but you will need the jack stands you mentioned.

That having been said, you can get by with tightening the bolts and then checking the fluid level often.

As 'rewatson5651' says, personally - I'd deal with it rather than let it leak.

You have indicators for coolant level, engine oil, and most of the other important fluids in the car, but NOT for the differential. This means that you'd need to stay on top of the rear diff gear oil level to be sure it never went dry, and if it did you'd be looking at pretty costly repairs.

"A stitch in time saves nine" and all that. It's not that hard to do, but I'm a thousand miles away and sitting in my comfortable office...

Good luck,