I would really only trust "airsoft" or "paintball" brand silicone spray. RC shock oil (IIRC?) is supposed to be good too.
A lot of bottles at hardware stores will say 100% silicone spray, but it will still have petroleum products in it. For instance, I bought a bottle of Ace Hardware 100% silicone spray and tested it out on an old BE AUG body to see if it was safe for plastic. Let it sit for a while and when I came back, the parts of the body which I sprayed (which used to be black) were a gray color. Needless to say, I wouldn't want to be spraying that on my compression parts or on my bucking.
Here's a good guide to read through:
http://www.airsoftforum.com/board/Airso ... 14544.htmlNotice how many "ingredients" you have to watch out for and keep in mind some bottles don't list everything that's inside the spray. Seeing as it can be such a hassle, I think you are better off getting it off an airsoft website. ICS silicone spray comes in pretty good sized bottles, so it will last a pretty long time. (especially considering you don't really need silicone spray for much)
In all honestly, I found silicone spray/oil not to be the greatest for compression parts. It doesn't stick well enough, so it sprays through the air nozzle and into the bucking/hop up chamber. That reduces the friction (which may sound like a good thing, but it isn't) and creates gunk that reduce the performance of your hop up system. You are better off with a grease/gel IMO.
White lithium is great for gears though.
I would think that UTG silicone spray should be fine, seeing as it's an airsoft brand.