Can you use dish soap in cleaning radiator?

Do not use a dish soap or any dish washing soap to the coolant system to flush. Any soap in the system may start eating the engine blocks and could cause failure.

Dish soap is stronger than detergent that is used for clothes?

When it will be used for cleaning, detergent is stronger. Though you should not be using any soap. When you clean a radiator, add 5 tablespoon per 1 liter of water.

Thank you for the recommendation.