Engine light remains on. Added coolant. Added oil. Thinking might be a gasket

they are known for bad head gaskets and intake gaskets, have it diagnosed at the shop and don't drive it or you can do serious damage to the engine.

Head gasket or cracked blocked

Look on the back of the engine for antifreeze-either by number 1-2 cylinder or back by the brake booster. It is a know problem with Saturn engines, leaking by the rear intake. Check under the surge tank, they crack and leak too-check the bottom of the water pump for leaks, it has a weep hole that, if the seal inside is broken, will leak. you need to look for symptoms and evidence of leaks-if there is no obvious leaks from hoses, or outside the engine anywhere, it may be a head gasket-check your oil for a milky texture, or greyish color. check the bottom of the surge tank for oily residue, and look for smoke coming from the tailpipe.

Usually coolant have special markers which shine in UV light, so you can take an uv lamp and check for leaks.
Also check oil level and color (it shouldn't be white, if so coolant - runs into oil, serious repair needed)
Also their should be no white smoke (more or less) from exhaust pipe.. if there is - the gasket is damaged and repair is needed.

In conclusion - there are three ways to loose coolant: leakage, leakage to oil, leakage to combustion chamber.

Sounds like blown head gasket soery

depends on the type of oil in the reservoir!! Typical issues that will cause this on your 4.2L I-6 engine; 1. (usually pink/reddish oil) trans fluid leaking via faulty radiator, blown head gasket from overheating (severe), or someone accidentally added oil to your radiator!!

You have most likely blown a head gasket,or cracked ,or warped a head.

white smoke out off exhaust is coolant getting into cyl like a bad head gasket to much fuel would be black smoke

sound like intake gasket leak.it will leak oil into the cooling system.

You did not mention what engine you have, so I assume it is a 2.4L and has any radiator stop leak been added to the coolant system lately?

If no radiator stop leak has been added, the good news is you don't have coolant in the oil.
I would speculate you have a head gasket problem. The oil pressure is higher than the coolant pressure, therefore the oil has the abiltiy to enter the cooling system. There is an oil pressure supply galley that runs between the engine block and the cyliner head to supply oil to the cam followers. That is most likly where the oil is getting in.

Unfortunatley the head gasket will have to be changed.
Let me know.
Regards,