Oil in my radiator

Does the engine oil level go down? Does the trans oil level go down? If not I would think it was in radiator before. Oil is lighter than water or coolant so it will be at the top. Also I would suck it out of the top instead of drain radiator so you don't get it in whole radiator. Doesn't take much oil in top to make you nervous so you might not have much contamination. You can buy suck gun from parts store pretty cheap.
Trans level is good engine oil goes down but I'm chasing a oil filter adapter leak also. And your exactly right it's not a lot of oil but it does make me nervous. Good idea about not draining the oil all they the system suck it out of top. Thanks Dustin