overheating subaru forester on 2001 Subaru Forester

recently having problem with temp gauge going in red while driving very short distance coolant level in resevior good no smoking from hood but has burning smell.recently had bad oil leak which was said to be fixed but still leaking small amount on ground.went back to follow up on leak told the small leak not coming from same area not a issue due to age and mileage of car[152,000]states overheating may be thermastat due to guage fluctuating while at shop told to return if continues since then problem more frequent

Asked by for the 2001 Subaru Forester
Possible Cylinder Head Gasket problem.
Check for any coolant leaks coming from the cylinder head gasket.
We have seen head gasket failure and a few with cracked heads causing air pockets at the thermostat as well.
Check if the lower radiator hose is cool when the engine is hot. If so, the thermostat is not opening. Possible air pocket behind the thermostat preventing it from getting hot and opening. Verify Heater core return has flow and there are no external coolant leaks, which could allow air to get into the cooling system.