The Wacky Wednesday Special for January 4, 2017 is 40% off the Gamblin Oil Painting Medium sampler set. The set includes 2 oz bottles of Galkyd, Neo Meglip, Refined Linseed Oil, and Gamosol with a 37ml tube of Galkyd Gel and a 2 ml jar of cold wax medium.
Gamblin has a handy interactive mediums guide where you input the desired result and it helps you figure out which medium will produce that result and a downloadable medium guide, Gamblin Oil Painting Medium Guides
Robert Gamblin gave a blog talk on Artists Helping Artists a few years ago that is a wonderful source of information on mediums and oil painting. Robert Gamblin Interview