The cooler has a 'pop off' by-pass as the filters ,BUT in normal operation,yes all the oil goes through the cooler plates SOOOO....those of you who had an engine blow...did they put a new cooler on? as the plate type coolers tend to retain debris???.The plate type cooler does help for oil warmup but if you are considering a better than stoc upgrade look at the 'Laminova' re Mocal or 'Think Automotive'
