Combines Coolant alarm problem

The oil is a good possbilty that is causing the low coolant level alarm. you need to get to oil out of the rad first. A good detregent either laundry soap or dishwasher soap perferrable liquid soap. will get the oil scum out of the rad and also make sure you haven't had a oil cooler failure again. After getting the oil out of the rad. if it possible to get the probe out of rad clean it off or replace it. Hope this helps

have you checked the wiringIJ I've had machines that the wiring was broke or more common chewed up by mice,(usually up around the rad some where). I think theres a module just for the level sensor, but I'm not sure if it applies to the 80's or not. Hope this may help.