car is overheating.

I drove all day today & there was oil in the car & water in the radiator. The car was fine until about 6 pm & then all of a sudden it was all ther way to H. I parked the car & looked & the water was boiling in ths overflow.It looked like there was a little steam from the radiator as well.I had to go inside & later I looked at the overflow. It was a little low on water so I put more water in because I had to get home. I've noticed a little fluid on the ground when I park, but it doesn't over heat until late in the day. What do you think... thermostat, water pump, fan....? I'm going to have someone look at it because I don't have a lot of money for a diagnosis,,,but, I sure don't want to hurt the engine by overheating.The car is a 2008 chevy Aveo with about 70,000 miles. I think I have a leak in the AC unit as well because all the freon is gone from last summer & we just filled it last summer.

Because it happens late in the day, I'd say - but its still just a guess- that its the fan. If it was the thermostat (stuck shut)it would likely heat up right away.

if it was the fan it would start to over heat every time you came to a stop once warm and cool down once you started moving (like an actual speed not in traffic).

if you saw smoke from the rad, and even think you have a leak in the AC its probably a leak in the radiator. As well as the condenser.. from a rock or something. Look through the grill, and front under the bumper, you will only see the condenser the rad is behind it. But the fins should look uniform, any dings dents etc could be a leak. Same goes for the rad, look for where the stem came out..

A slow leak seems most likely for late in the day, especially if you have been filling it up. If you want to try bars leak or something you can, but it only delays the inevitable. but could last a few months or a year. it also puts a bunch of crap in your system.