I use wd40 to flush ignition and door locks etc out then graphite powder lube to keep them lubed
This stuff is great for any ignition locks and stiff padlocks etc..http://www.ebay.co.uk/itm/291803898148?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
I did a bit of research on this and found that graphite lube is great stuff on dry locks, but not so much in wet conditions when it turns into a mush.