I have a 91 Honda Civic, 4 days ago someone put oil in my car and didnt put the cap on all the way and oil leaked out all over my engine, yesterday my car overheated. I put antifreeze in and it seems to be leaking out of bottom of radiator(?) and it is still overheating, what should I do? Is it the radiator?

Do we have oil in the crankcase yet? does it look normal or frothy? Did they put the radiator cap back on?....man, I'm never comin' to THIS mechanic again__ Leaking out the bottom? a hose blew? crazy stuffed a screwdriver into the fins? "mechanic" left the petcock open? put a pressure tester on there (borrow from an actual mechanic, or buy one [under fifty bucks] pump 'er up to 17 psi and watch the geyser show---- with any luck simply tighten the screw clamps, refill with 50/50 antifreeze and off ye go.....after putting a BRAND NEW oil cap on there [tons available everywhere, don't mess around with used] HTH (really hate those guys that close with that. hop those horses~

yes I replaced the oil!

Also when car overheats the radiator is still cold

First you find and fix the leak. Fill the radiator, run the engine to get the air out and fill it some more to top it off. If you don't have enough coolant, it will over heat and cause engine damage.

if it puts your mind at ease, you could run it without the thermostat in place, that way we'd know if the waterpump was workin' okay~