Major oil leak after oil change
 

I recently (2 weeks ago) bought an '86 300SDL with 201,000 and I was quite happy until today. I noticed a few small oil spots last week but nothing major. On Saturday I changed the oil and filter for the first time, and everything seemed fine (8 qts to fill it). Pressure jumped up to 3 and stayed there within seconds. I didn't take the car out yesterday after changing the oil, but today I ran a few errands and drove maybe 15 miles total. On the way back home I noticed the low oil light was on (never happened before), and the "Antilock" light came on also (don't know if this is related, or some other problem). When I pulled into the garage I left it running, and I noticed that there was a steady stream of oil running from the back of the engine (drivers side). I turned it off, and the steady stream of oil slowly stopped. There was no oil on the dipstick so I put in almost 2 qts to bring it up to where it ought to be. As I started the car again, I noticed that the glow plug indicator light did not come on when I started the car (is this only a cold weather thing?), but it started OK and the pressure jumped right up to 3 again. I have it parked in my garage now and I'm puzzled as to where I lost these 2 qts of oil. The filter housing looks fine and I can't see any other obvious problems. Any help would be greatly appreciated.

pointing the obvious, but at times the filter is not placed and screwed in correctly. see if that's where the leak is coming from. the other one would be the drain plug. Once you have these two checked perhaps someone else could chime in for further troubleshooting.
good luck.

Did you tighten the oil drain properly?

Drain plug
 

The drain plug is definitely secure. The shower of oil was coming from the back end of the motor.

Filter post with O-rings
 

I'm somewhat concerned about the post that runs through the middle of the filter, and the nut on this post that is on the top of the filter housing. I'm not sure if I need to tighten this or loosen it, or what to do with it. I'm not certain what purpose it serves, and I didn't know what to do with it. I know that I did not replace these O-rings, but I can't imagine that this has caused me to lose 2 qts. or oil over the course of a 15 mile drive.

Leak found
 

I found the leak.... it was the U-ring. I'm sure it was an O-ring when I installed it, but after having pinched it between the filter housing and the lid, it cut it into a U-ring.

If you're changing your oil for the first time, I can't stress enough about triple checking to make sure that the O-ring is seated properly. I'm very lucky that I was close enough to home.

Thanks for the support, I won't make that mistake again.

Same thing happened to me last change, the O-rin dropped into th canister as I tightend the lid on my 617 and it barfed oil EVERYWHERE when I fired that thing up, had pressure, thank god. I got as far as the other side of the garage door before I noticed the litre per foot oil trail...LOL