Check out this posted topic of about 2 years ago...
About three postings from the last I show how I scratched a typical oil column using Plastruct styrene components. Not hard to do....seems to have enough credibility to fool my 1:48 oil-burning steamers into pulling up along side of it.
If you do a forum search you'll find a bunch of past discussions on the matter...
FWIW, always....
KD