I gotta be out of the house by 7:00 every morning for school so I usually only have time to let my car sit for about 30 sec to a min which is good enough then on the way to school I never bring it over 3k rpms. I think this should be done winter or summer. But 5-10 min, come on man dont you think thats over doing it a little? Some of the time I dont let my car sit at all I just turn it on and go, but I still dont bring it over 3k until the needle goes up a little. But about letting it sit for a couple minutes, I dont think it really matters. But I do think its a good idea no to bring it above 3 or 4000rpms until the needle goes up a little.