What removes oil and black undercoating but not paint? Options

[mskala]

My car used to leak oil from lots of places. After rebuild, now everything's pretty
good. But, particularly from under the oil tank area, oil has got on a large area
under the floor and longs.

I found accidentally that the CRC Electronic Cleaner doesn't seem to remove paint,
but it is so weak that the black undercoat (wurth?) turns into a huge amount of black
goo that hasn't really come off the car.

I want to save any paint and the white-ish undercoat. Any products that will do this?
I assume my paint is the old lacquer type paint.


Thanks
Mark S.

[930cabman]

Simple Green