The most important time to use a pump saver product on a pressure washer is when you are going to be storing the machine for longer than 30 days or at the end of the season before the cold weather hits. However, if you only use the pressure washer 3-4 times a year, I would suggest that you run a pump saver product throught the pump after each use. This will give you the longest lifespan possible out of the pump.