There is oil in the radiator

Most likely you have a blown head gasket allowing oil to get in to the coolant.

Check the engine oil dipstick if it is mix withe water don't drive
and check the gear oil
some cars got oil coolers
when it leak it's mix with water

Your engine cooler or your transmission cooler has failed and the fluids are mixing in your radiator. Note the coolant is corrosive to the internal bearings to your transmission and engine. Determine which oil is mixed in your radiator, pull the dip stick on your transmission and engine and look for any signs of coolant mixing. Try not to rung the engine and flush out the engine or transmission before the bearings or damaged and will cause you to replace the engine or transmission.

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Could becoming from ur oil cooler lines that go into rad,,,could have internal crack in rad,,,pull dip stick out & ck to see if motor oil is low or a grayish color,,if ok ck trans fluid to see if is low,,have to find out what kind of oil residua is in the over flow jug