O-Gauge Diesels and their Plastic Shells

Smart move.  You did it right.

Clever idea. Since you wiped off the residue, I'd think the plastic would be fine.

 

Tomlinson Run Railroad

An old method that works well even on wood projects. Of course in the old days we used bar soap. I don't think the liquid soap will hurt anything.

In over 50 years of fiddling around with plastic shells on trains, I've discovered that if a screw is hard to tighten back into a previously threaded hole, you are probably cutting new threads in the plastic.  The trick is to place the screw back into its hole and slowly back off the screw until you feel the screw's threads reengage with the previously cut threads in the plastic.  THEN screw it back into the shell's hole.  If you are cutting new threads, you will eventually enlarge the hole so that the screw will not hold. 

 

Using dish soap as a lubricant may not harm the plastic, but it shouldn't be necessary.  Good idea to lube the bearings before using, though. 

IT's a good idea to always clean the threads of the screw that was removed before reinstalling. I simply hold the screw between my finger and thumb and turn the screw  counter clockwise pushing my thumb nail into the threads.
Romiller