engine oil in radiator cooling water???
WHAT - who came up with this lame idea anyway, if a system calls for 50% mixture of glycol based coolant with water, then why not follow it?
it can be reused again by collecting it all in a pan and then put back. I know that mechanics/AC simply let it drain onto the ground, take your own clean tub/pan/cut up bottle and collect all the coolant to put back in the system.
The coolant itself needs to be changed every 2 to 3 years. And dont open the radiator cap everyday (God only knows why our people love to do that) - check from the expansion tank, if its low add some coolant mix to it, if its overflowing then check the radiator level as its not sucking coolant back.
Its quite funny what sort of short cuts we come up with, not too long ago there was someone advising to put half a litre diesel fuel in the cooling water, How crazy can one get, all petroleum based oils will eat away the rubber parts of the cooling system.