I used the raw linseed oil/solvent to oil out a dried (only a few weeks) painting and somehow got a completely unworkable glassy surface which I then had to sand down and repaint the whole face. I went on to research further and found websites dedicated to the technical side of painting. (
http://www.amien.org/) (
http://rourkevisualart.com/wordpress/) (
http://www.tadspurgeon.com) which pretty much say of oiling out, "don't do it." Mostly, the conclusion seems to be that it's the rawness of the oil rather than the type of oil. Raw oil isn't so good. Tad Spurgeon's site is a long, hard read but worthwhile. The formula I'm using now for retouching is Oil of Spike Lavender (1 part) and my own home-produced walnut sun oil (1 part.) Robert Doak in New York sells sun oil if you don't want to make your own.
I'm certainly no expert, but any of the guys with those websites will talk to you about these issues.