The first thing you should ask is why is the truck overheating? An overheating engine can cause the oil light to come on. It isn't good news and could lead to a seized/wrecked engine.
There are a number of causes of overheating including stuck/faulty thermostat, leaking radiator/pipes .. and a faulty head gasket.
The sloshing noise you describe is probably hot coolant/air within the heater matrix/pipes.
You need to have somebody look at your truck and find the cause of the overheating. Fix it now before things become very much worse and expensive...
Answers & Comments
The first thing you should ask is why is the truck overheating? An overheating engine can cause the oil light to come on. It isn't good news and could lead to a seized/wrecked engine.
There are a number of causes of overheating including stuck/faulty thermostat, leaking radiator/pipes .. and a faulty head gasket.
The sloshing noise you describe is probably hot coolant/air within the heater matrix/pipes.
You need to have somebody look at your truck and find the cause of the overheating. Fix it now before things become very much worse and expensive...