I run my engine for about 10min before I use my Mityvac 7201, temp hasn't been an issue. I use the largest tubing that will fit the dipstick. Insert the tubing until it hits the bottom of your oil pan, then withdraw the tubing just a bit so it's not in contact with the pan. Start pumping about 10-15 pumps, let it take up what it can on that amount of suction. Once it no longer has sufficient suction, I'll pump the vac again a few times. Once you start pulling air, sounds like little metal pinging, you can advance the mityvac tube fully to get any residual.
I have a plastic bag waiting immediately for when I remove the oil filter, wrap it in the grocery bag and tie it off.
Arthur John "Destroyer of Sleep"
Sean David (has more rolls than a bakery)