CLP by Break-Free. I've used it on my semi-auto shotgun for many years, shooting upland birds in temperatures down to -20 degrees F with no problems, at least not with the gun cycling properly (couldn't say the same about the dogs or me at those temperatures). I've tried a few other products that did slow the action down or totally seized up in real cold weather, but haven't had it happen with CLP.
You mentioned the action closing slowly. I try to use very little on the action when getting ready to use it in really cold weather.
I looked at the website for TSI 301 that was recommended above. It showed a comparison to WD-40 and states that TSI 301 has a pour point of -60 degrees F while WD-40 pours down to -100 degrees F. I've tried WD-40 many years ago, and had it seize up my gun at temps below zero, and was part of the reason I ended up going to CLP. Based on pour points, it looks like TSI-30 could seize up at warmer temperatures than WD-40, so I'd assume they'll both seize up at temps warmer than what CLP will function in.
Last edited by seppli; 01/18/13. Reason: Add comments on TSI 301
