Join Date: Mar 2002
Location: Austin, TX, USA
Oil in the coolant will puddle on top in the radiator. It will tend to be frothy like a milk shake. Brown coolant usually is just overdue for a flush. Rust turns the water brown. There can also be some frothing from bacteria. Oil froth is very easy to spot...it will coat the cap with foam. If your suspecting oil, drain the oil and see if antifreeze comes out from the bottom of the pan.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI