Most of the liniments won't start having a lot of kick until you start sweating. So while it won't really cause any "loosening up" like you might experience with something like... a microwaveable heating pad, it will start to kick in after you start training.

Blue heat is good. I have not looked at it in a while. I just know I can get Absorbine at the local farm supply store and that I like the smell and it does the trick (I tend to use it directly after a workout, leave it sit for 30-60 minutes then take a nice hot shower).

If stiffness is an issue, something else I can "prescribe" is to purchase some Tommy Kono knee sleeves. If you buy up a size you can probably manage to get them over your thigh. The neoprene rubber sleeve is non-constricting and does a great job of building up a sweat. I use the knee bands on cold days and it pretty much clears up any knee stiffness I might have been feeling, before I ever touch a weight. I also use the "belly band" to help warm up my lower back. It isn't like wearing a belt, there is no support and it still allows me to breathe. But the extra heat generated is great for the old lower back region!

Don't use bands with linament