1993 Mazda 929 white smoke

For the last two week the engine light has come on, and sometimes the temperature gauge goes up, espically when I'm idle, but today there was white smoke coming from the engine, with a sizzling sound. There is no weird smell, but the temperature goes up. I put oil in the engine, but that did nothing. I havent had a oil change in the last three and a half months, but I have not reached my 3000 mileage point. Help please.