I have a '96 mitsubishi 3000GT and it keeps over heating. I've had the thermostat replaced twice and am constantly changing the oil. what could be wrong?

Mitsubishi electric had a problem with ecm's going out on those years they used fish oil in the capacitors with heat and cold temps change in time will leak and cause shortage in pcm board , have it tested by someone who knows electronics , ecm behind passenger kick panel

Radiator is either clogged,or it's bad. You could also check the heater core.

The light will go off when the fault that caused it to go on is repaired.

sounds like an electrical problem with the guage. Do you get constant heat or intermittent?

may need a new water pump butr sounds like the empella just needs replaced

UNfortunately the mitsubishi transmission are very particluar about the oil that is in them and how good/poor its quality is..........if you are unsure whether the transmission fluid has been replaced, I suggest that you would try this first.....and this should eliminate most if not all of your problems........I just hope it is not too late !!!!!!

white smoke usually means a blown head gasket or cracked head but first check the pcv valve if its stuck open your engine could be pulling in oil and burning it raw, if not good chance its your head gasket.

Replace the fan resistor located under dash near passenger side on the side of the heater box.

The mechanical water thermostat on the 3000gt is right under the metal water cap just to the left of the engine and next to the spark plug wires. The cap will have a warning about not opening if the car is hot as the water is pressurize and can spray out. If you want to replace the thermostat I recomend you use a genuine Mitsu thermostat. I beleive all years, base,SL and VR4 are the same but have a look at mentor mitsubishi http://www.trademotion.com/partlocator/index.cfm?siteid=213934&year=1993 for the right part and useful images. They also have a good discount price. Select your year, then make and model and look under COOLING SYSTEM->COOLING SYSTEM->THERMOSTAT.
Another useful place to look for 300gt information is 3si.org and stealth316.com
Replacing the thermostat you will lose some coolant so be prepared to catch it and top it back up afterwards. You will also need the rubber gasket that goes around the thermostat if your's is old.

Does the engine knock? Low oil pressure? Why does it need bearings. If the bearings are bad and you don't remove the crankshaft to have it turned, you will be doing this job more than once. no fun