I have a Honda GC160, 2.2gpm, 2400psi pressure washer. How much and what kind of oil do i put in the pump? I wasn't getting much pressure so I pulled the pump apart.(bad move)

We are talking about the water pump here right . A stright 30 weight and it for that size pump about 14 ounces .4 liters look at the little window on the pump on level ground it should be at the half way point . If you want to buy offical pump oil the # is AW-4085-0016 This is MI-T-M spec but with this # you should be able to cross refferance to your pump make in case there is an issue with detegent or non detergent oils it could be an issue for the seals . But its basicaly 30 weight oil