my intercooler are dirty with oil and sludge
it is advisable to use a degreaser (spray type) to spray on the intercooler/radiator/aircon radiator/oil cooler and etc, then use water to spray away?
should i use spray the degreaser when:
(1) engine is hot
(2) engine is warmed down (after 1 or 2 hours of rest)
(3) engine is cold