O.K.: changed the oil & filter yeasterday ('89 5251 M20). This morning the radio, electric windows & automatic door locks all do not work. All fuses are good.

I can't see any wiring that I could have mangled during the work. Can anybody think of anything that I could have screwed up (did the filter from above, on the right side of the engine). Might be a coincidence, but we did get 2" of rain last night, so maybe a moisture short? But where?

Sounds like the fusible link http://bmwe34.net/e34main/maintenance/electrical/fusible_link.htm

Hoboclown, you hit it on the head, & THANK GOD!! I was coming back on to give an update, that my kid told me it started happening after he went in the trunk last night. Because of that, I was getting ready to pull the trunk wire bundle to find the "short".
But you got it right, it was the fusible link, I didn't even know it was there, you saved me hours on a wild goose chase.
Is this a great forum, or what?

Thats why we are here haha