You have to bring Heather (only Heather, since she has the lube, and it will mention this each time you interact with her sexually) to
climax each time, while making yourself close to orgasm. If your close to climax, just enter into sexy times with her and up her pleasure meter once or twice, then exit, and when you enter again, your meter will be a little lower, or your click the wall and stuff to quickly lower it.
Eventually, after making her orgasm like 6 times, you'll be fully thawed and not have to deal with that crap anymore. You'll know if its working when your view does a close up of Heather looking at your johnson, and saying something different each time you exit the minigame. It's tedious, but that's what it is.
The dude literally four posts above you gave an explanation. Basically, you have to thaw yourself by going into the bathroom and looking at pictures on the book rack, then go back to Heather and "share your heat" with her, by letting her give you a hand job and shooting your stuff all over her.
After that try to use the Tar Pit, and keep selecting the options (i think I kept selecting the third one, with the heat tube), and eventually you can say "can't we try something else?", then you'll get the option about the lube, and fun times (and the literal sex grind) can begin.