I spray with a 6430  and a hydraulic  sprayer pump.   When the outside temperature gets above  90  the hydraulic oil gets hot and warming light comes on.  The hydraulic cooler is small and is mounted by itself in front of the radiator.   I asked the service manager about a bigger oil cooler and he didn't have any solution.   It seems like a larger oil cooler should solve the problem.   How would I get this done?   I would like to hear from someone who has had this problem and solved it.