Switching from Motorcraft synthetic blend to Costco full synthetic is an upgrade, not a downgrade. Full synthetic provides better protection for RV engines. Use 5W-20 viscosity and you are fine. Kirkland oil meets all Ford specifications.
Add minivan seats to your RV by mounting securely to floor joists with grade 8 bolts. Include proper seatbelts at each position. Elevate seats with plywood platforms if needed for clearance.
E-350 and E-450 use same V10 engine with nearly identical 8-10 MPG fuel economy. E-450 has heavier suspension, brakes, and higher GVWR. Choose based on weight capacity needs, not fuel economy.
Saginaw pump popular upgrade for older Ford chassis. Kit needed for proper installation includes bracket, pulley, and hose adapters.