broken radiator hose, cracked radiator, thermostat gone bad (depending on where its located) or water pump
The engine needs to be flushed.the coolant ports have a build up of gunk causing the engine to run hotter. The heated water expands to much causing it to over flow from the reserve tank.
That'll be your coolant, and there could be a number of things causing it... a blown head gasket will do it... a coolant leak where the coolant leaks onto a hot engine block will do it... a faulty radiator cap which opens too easily can cause this.... excess coolant causing the system to overpressurize and have to relive frequently will, as well.
If it is water, it could be a plugged up AC condensation drain or if it is engine coolant, it could be a leaky heater core.
The coolant temp. sensor could be bad....or the thermostat could be stuck shut.....there are a few things it could be actually
You can add turbo to any engine if you are willing to upgrade the engine properly. Turbo kits are generally rather expensive. Although they typically include everything needed to install the turbo itself, it isn't an easy task. Welding could be required. Drilling into the oil pan could be required. It is recommended to have a turbo kit installed by a professional.
A turbo usually adds around 10-100 hp, lets say 45. A turbo could be fitted to any car engine, and they already have an amount of hp so it could be anything. There is no proper answer.
maybe catalytic coverter clogged, leaking coolant hoses to/from heater core, hopefully this helps.
Don't worry about it. If the engine has not been damaged, all you need to do is keep the coolant reservoir full, and run the engine enough to get it hot at which point it will push out a lot of the air. After it cools again, it will pull in the coolant. Keep the coolant level up by checking it every time you get ready to go somewhere. You'll notice when the coolant level no longer drops. Note that if the engine has overheated, it could have been damaged. If that happened, there could be a failed head gasket or cracked head. When either of those happen, combustion gas is forced into the coolant space, forcing coolant out of the engine and causing the engine to overheat rapidly. Unfortunately, if that has happened, the only option is to replace the faulty parts and re-surface the head.
Could be low on coolant.
The coolant sensor moniters the coolant temperature. A faulty thermostat could cause the engine to run cool.
If the coolant reservoir can not maintain the proper level of coolant, it is possible the engine could over heat when the level drops.
If you have coolant on the top of the engine it could be a leaky thermostat housing or a leaking intake gasket.