This may make your bad day go a bit better.

Here's one, also related to oil.

I dropped a new 360 in my Duster, swapped a bunch of parts from my 318. Somehow I forgot to swap the oil filter plate onto the 360. The piece that goes between the block and the oil filter. But of course I didn't realize I forgot this piece until I filled the pan with new oil and started priming the engine.... so I wound up with 5 quarts of nice clean Penzoil on the floor of my garage. Oops.