Oil in water

[LONGJOHN]

Have 91 towncar with oil in radiator reservoir. Anyone know how this most likely to happpen????

[JustSayGo]

From a broken transmission oil cooler or engine oil cooler that is inside your radiator.

[Towncar]

Originally Posted by JustSayGo

From a broken transmission oil cooler or engine oil cooler that is inside your radiator.

Or:
Bad head gasket; Cracked Cyl wall; Cracked block; someone poured it in the wrong hole

[JustSayGo]

Because things flow from higher pressure to lower pressure it is extremely unlikely that Or:
Bad head gasket; Cracked Cyl wall; Cracked block; will result in oil in the cooling system. Leaks in blocks, heads, or gaskets result in coolant mixing with the oil in the crankcase. Oil pressure in either oil cooler is greater than cooling system pressure while the engine is running. Cooling system pressure is greater after a hot engine is turned off maybe as high as 16lbs psi. If the coolant has enough time to leak a little into the oil at 16lbs, just imagine how much oil at 60psi will leak from the same hole between oil and cooling system during the entire time the engine is running.

[Towncar]

Originally Posted by JustSayGo

Because things flow from higher pressure to lower pressure it is extremely unlikely that Or:
Bad head gasket; Cracked Cyl wall; Cracked block; will result in oil in the cooling system. Leaks in blocks, heads, or gaskets result in coolant mixing with the oil in the crankcase. Oil pressure in either oil cooler is greater than cooling system pressure while the engine is running. Cooling system pressure is greater after a hot engine is turned off maybe as high as 16lbs psi. If the coolant has enough time to leak a little into the oil at 16lbs, just imagine how much oil at 60psi will leak from the same hole between oil and cooling system during the entire time the engine is running.

Yeah, all that ^^
But it happens regardless ... you are correct about "most likely".... I overlooked that part of the question.