I have 95 M3 with s50 engine which recently will not get up to operating temperature. Today ambient temperature was 45 degrees and the gauge barely gets out of the blue area. I've also notice decrease in gas mileage. Could this be interconnected and would you assume that it most likely the thermostat that is bad? Also, have slight oil leak from front of engine dripping onto the line running to the A/C condenser in front of radiator. Anyone know that this is common problem and is there a fix? Thanks