yes it can be over cooled. if u are running a thermostat is should still get up to temperature before it opens to let the cool water in anyway, so should still run normal after heating up. if theres no thermostat then thats probably the problem.i think ca's run a pretty high thermostat, like about 195 F, and if its a turbo it will definately use more fuel if running too cold. also if its taking ages to heat up, u wearing out the bearings and bore etc more. u really should get up to operating temperature asap to eliminate as much wear as possible........