Almost killed my car

Started up the car this morning, oil pressure plummets. Turn it off, check the dipstick-empty. I ignored the oil smell I had been noticing the last week or two just attributing it to a side effect of a 20 year old open top car. The oil filter had loosened up. I don't of anything that could cause it to happen other than a failure to secure the filter after the oil change. I always check the surface for residue from the old filter. Put in 2 quarts I had at home and drove to work. Picked up more oil at work and topped it off. No strange noises so far, no smoke or loss of power. I guess this means I'm now qualified to be a quick-lube technician. Better check the drain plug just to be sure...

Yikes!

Lesson learned...don't change your oil and you won't have this problem.  Duh.

I have a Miata I bought for cheap due to the prior owner not fixing an oil leak... the bolt holding the oil filter 'adapter' (oil cooler sandwich) came loose, allowing oil to gush out.  I still need to tear down the seized engine to see if it's rebuildable.  The head was trashed.

I have seen this before. You got lucky. 

The wife's Mazda5 got a K&N oil filter once because they were on sale as part of the "oil change deal" at whichever FLAPS I wandered in to that day.  I didn't notice the puddle in the garage, but after a couple days I heard the sewing machine sound when she started it up and freaked out.  It hadn't lost all its oil, but the filter was loose enough that it needed a big top-off.  I guess you need to crank down that hex head they put on it in order to make sure it's secured?  I dunno.

At least I didn't catch that one on fire...

Probably did some damage to my SL when I had a similar problem. Noticed the lifters clattering after a 40 mile drive where I got bored and revved out 2nd and 3rd a couple times. 2 quarts of oil and magically it's quiet again. Culprit was a loose filter. 

I was ready to accept the loss and start pulling parts to sell as soon as I saw the pressure drop. On a positive note I feel like I got a free car.

Now I have to do something about the oil-water mess in the garage that I thought was just water.