Cold radiator

[corey170]

The whole driver side of my radiator is cold, but the passenger side (where the hoses are) is really hot. Now I've heard that this could be from my thermostat not opening, but I can drive for about 20 minutes before my car overheats. It sounds like a bit of a clogged rad to me (Yes I used that liquid headgasket sealer in the past, now maybe its kicking me in the a**). If the stat wasn't opening, then wouldn't the car overheat pretty quickly?