Coolant in the engine oil

There is the possibility of the intake manifold gasket leaking coolant into the intake tract and getting into the combustion chamber. It would then be found in oil.

Just to add this one there is no engine oil cooler on this engine.It only has the transmission cooler in the radiator tank. You could have a cracked block or cylinder head here is a guide that can help.

https://www.2carpros.com/articles/coolantantifreeze-in-the-engine-oil

Please go over this guide and report back.

You listed the wrong model the SL2 only has a 4cyl engine if you listed the year correct then you have a L300 or a LW300 depending on if its the sedan its the L300 if its the wagon its the LW300. Never seen the head gaskets mix oil in the coolant. But have replaced a ton of the oil coolers for leaking oil into the coolant. So who ever did the diagnoses on that car I hope you didnt pay someone for that and to replace the head gaskets. Otherwise I would ask for a refund.

Alright if its a sedan you would have a LS2 model and if its a wagon you would have a LW2 model so you know next time what model you have. The caddys use the same engine as your car but with a different intake manifold.I would replace your oil cooler with a caddy oil cooler there built better then the one used in the saturn. Its in there catera model. You can try leaving the guy who fixed your car in your garage a message of if he doesnt return your call your going to take him to small claims court.

Its cooled by coolant I already told you I replaced a ton of oil coolers for mixing oil in the coolant. Its under the oil cooler plate under the intake manifold. You cant miss it there is two good size steel oil cooler lines going to it. The lines come out of the block by your oil filter housing and run up to your oil cooler.I would replace it with the caddy catera model cooler there usually cheaper and sturdier. You will need silicone I would get the gm silicone it calls for. You also need the steel oil cooler banjo washer seals for the lines and the o rings for the oil cooler plate.