It ejects water at very high pressure that it can loosen hard to remove dirt and grime on just about any type of surface. In fact, some pressure washers are so powerful that it can even damage your wood deck if you re not careful using it. However, you have to keep in mind that if you are going to clean off grease or grime, you are better off using hot water or steam pressure washer. However you need to remember that although it may seem that pressure washers are very easy to operate and that they are safe to use, you still need to keep in mind that they are power tools. Improper handling of power washers can result to injury, which is why you have to know how to safely operate this piece of machinery. This increases the speed and efficiency of the entire cleaning process. For the flow rate, choose a pressure washer that offers 2 gallons per minute or less. This is perfect for cleaning automobiles. You really don t need a high flow rate to get the job done and you want to be efficient as well. So, getting a pressure washer with a flow rate of 2 gallons per minute or less is good enough for auto detailing. You can use the soap attachment with a cleaning solution to get rid of grease and grime under your barbecue grill. Then, before the soap dries on the deck, wash it off with the high pressure washer. The high pressure will help remove stains and loosen or remove dirt on the patio wood deck. Just remember to spray the deck with the nozzle remaining a constant 12 to 14 inches away from the deck. Don t wear your swimsuit or a board short and flip flops when using pressure washer. Instead, wear long pants and shirt. This will help prevent debris bouncing off the house to injure you. If you can, safety goggles must also be worn. You should also protect your hearing by using earmuffs and wear sturdy shoes. There are muddy footprints all over the floor and grease and grime under the barbecue grill. As you can imagine, this type of mess can be very hard to clean. However, by using a pressure washer, the pressure will be able to loosen the grease and grime as well as other stains on the floor. Pressure washers can also be used to clean cars.