Karcher 2500 PSI Pressure Washer "honda gc160 oil specs" Questions

...is a black, unscrewable oil cap, with blue-ish oil in it, BUT NO DIP STICK! How do I check the level? What kind of oil, specs etc? Thanks! ...

...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 ...