After much research on this subject, I went with Super Lube Dri Film (link below). I bought mine from a local locksmith who recommends it to his customers.

I've been using it regularly on both cars for several years and after spraying it into the ignition lock, you can easily tell the difference when inserting and turning the key. I spray both cars about once a month. At the price of ignition locks, I figure ten bucks is cheap insurance.

http://www.amazon.com/Super-Lube-11016-Aerosols-Dri-Film/dp/B000RFRM4U/ref=sr_1_1?ie=UTF8&qid=1437768940&sr=8-1&keywords=Super+Lube+dri+film