oil in radiator

Just picked up a '97 Astro LT w/ 4.3L V6 w/ 152k miles for $700. previous owner said he saw antifreeze leaking. when i opened the radiator resserve I found oil in the antifreeze. could this be a cracked maifold or just a bad gasket? engin runs fine otherwise. the oil on the dip stick looked ok. needs to be changed but nothing out of the ordinary. any suggestions.

thanks

How much oil in the anti freeze? Was it just oil or mixed? If it was just oil, maybe the previous owner accidently put oil instead of antifreeze in the reservoir. You mentionned he told you there was an antifreeze leak. Mistakes do happen.

Before thinking of the worse. I would do a cooling system flush, put fresh antifreeze and see if you get oil in it.

check the radiator for bubbles when the engine is running. before it gets hot of course! also is there water in the oil? with blown head gasket you will usually find anti-freeze in the oil...the oil will be discolored and show signs of water. best way to tell is to drain the oil. another way to tell is if there is a lot of steam (white smoke)coming out of the tailpipe..and then theres the always fail safe way of the cylinder leak down or the compression test. good luck

another thought...sometimes when 2 different kinds of anti-freeze are mixed (red dexcool and regular green anti-freeze) and it gets all mixed it will look like a little oil in the reserve tank...the 2 should not be mixed but it happens all the time. give it a nice flush and stick to the correct anti-freeze (red dexcool i believe...but it should say inside engine compartment) then go from there

i flushed the system this weekend and added new red dex-cool antifreeze. will look at it again in a few days to see if new oil is in the system. fingers are crossed. and thankx for the post.