I've always avoided using a flush of any sort. I only ever flush with clear tap water and then replenish with the correct mix of coolant and water .
However, I have a car that the oil cooler had let a little oil into the coolant . When I fit the new oil Cooler I want to flush the system and remove any traces of oil for obvious reasons.
Can someone recommend a flush ? As I say I've never used any sort as I was always led to believe it can cause issues .

Tia