Can't help you with the quantity or filter but Mobil 1 Fully Synthetic is very popular for gas engines. Depending on your mileage/wear on the engine will determine which weight you will need. I would try 10 W 30.
Jon & Sue Francis (Retired U.S.A.F.)
Lil Girl-Rescued, Abby Rescued, Peaches Rescued
06 Allegro 35TSA Workhorse Chassis
2013 Chevy Spark Dinghy