I am new here and not a motor kind of person, so forgive me if my question seems stupid. My son has a 1990 F150 with appx 110,000 miles. He went to check his oil a while ago and there was alot of sludge on the dipstick. He ran it up to the mechanic we use and he said looks like water got into the oil,etc.,etc. He indicated the headers and gaskets were in need of replacing. It was low on oil and anti freeze. We have had a couple of really cold nights. The truck runs and sounds the same. What have we done and how much will it cost me? Thanks.

Matt

 

C'mon folks.

 

You might want to pressure test the cooling system both cold and hot for a starter.
Then if nothing shows change the oil and fill the cooling system and see what happenes again.