I'm not sure what PSI the light is set to come on at but if your lights on you need to get a gauge and hook it up to your engine to see what you've got. It could just be a faulty oil psi sensor. Hopefully it is cuz otherwise you've got a lot of different things it could be.

I doubt the frothing would cause the low PSI but I wouldn't 100% rule it out. Depends on how much over it is and if you JUST changed the oil on it and overfilled it then that could be it.

If its not frothing or a faulty sensor then it could be a worn out oil pump, worn main crank bearings, something faulty with your oil pressure bypass/relief valve, a bad gasket in the oil pump circuit ect.

I'm assuming the car your talking about is the 04 GTP in your sig. How many miles are on it and how you drive it may help narrow down what it is.