Most single cylinder Briggs engines hold 40 oz of oil. SAE-30 type oil
it will hold about a half quart of oil
64 oz per the manual.
1.42L or 42 oz. If new oil filter about 4 oz more. Monitor as you add
20 oz. if fully drained, 16 oz. will usually be used in an oil change.
I will guess it is a V-twin and that would make it about 2 qts. depending of if it has an oil filter and which one.
For the engine, not the pump, 10W-30 is what Briggs puts in them, but SAE 30 is acceptable if your are not running the pressure washer in cold temperatures. I highly recommend you use synthetic oil in any air cooled engine.
1.5 qts of Oil
Most Briggs engines that small take 1 pint of oil .
5W-30 Full Synthetic at any temperature range 30W if outside air is above 40 degrees 10W-30 if above 40 degrees
Click the link.
56 ounces