I've been researching my impending oil change for about two weeks and feel I'm very close to crawling under my Precious to begin the process. However the numb nuts dealer from which I bought my filter did not include a gasket nor did they bother to mention I needed one - I'm clueless when it comes to working with a wrench so I didn't know to ask. I did ask for a drain plug seal which they gave, er sold me. So I'm good to go there.

Is it imperative I replace the filter seal? I'd rather not give them a penny more of my money. I'll keep buying from Suncoast et al.

 

Though you may be able to get by with the old, it is best practice to replace it every time you change the oil filter. Tip: Always run your finger with oil around the gasket before you screw it back on and always hand tighten the filter when installing.

 

You can get by without the seal. You can go many changes on the same seal, though since it usually comes with the filter, you might as well do it. Are you sure it isn't inside the filter box? Usually them come with the filter together.

 

I strongly recommend you go back and get the seal (it's not in the box?). Though it likely doesn't matter, it's SOP to replace it, if you get a minor leak it's a mess to go in and reseal, and if it's a major leak, well, it's a $100K car.
Since you're doing it at home, make sure the motor is warm when you drain it (wear latex gloves - much safer for lots of reasons), drain for an hour or four if you can, put that thin bead of fresh oil around the seal, and torque the plug (with new washer) and oil filter to spec.
Then underfill your car (just slightly, say 1/2 quart or so) when you refill it. Run it, then let it sit for 20 mins or so (on level ground) and top off to taste!

 

it should be part of the oil filter package.

 

Our kits come with the oil filter, rubber seal, and the crush washer (if applicable).

 

My M3 uses a similar rubber seal. I usually change my own oil except when I do not have access to a garage or a lift. A few years ago I was on a coast to coast road trip and I stopped into a place in Missouri to get my oil changed. They forgot to put the rubber seal in which was not a big deal until I got back up to speed on the highway. Once I hit about 80 mph on the highway smoke started billowing out of the back of my car. I pulled over and popped the hood. Most of the oil in the car was all over the engine and burning off the of the headers and exhaust. Long story short, make sure you use all the rubber seals.

Jason