I'm just getting into the whole oil wash thing, but I've been thinning with Mona Lisa Odorless Thinner. I've tested it over bare enamel (White Ensign Coloucoats) both on a scrap plane and on some landing gear doors. Zero issues.
On the Bench: 1/32 Trumpeter P-47 | 1/32 Hasegawa Bf 109G | 1/144 Eduard MiG-21MF x2
On Deck: 1/350 HMS Dreadnought
Blog/Completed Builds: doogsmodels.com