We do suggest using a fuel additive every time you fill your fuel tank. This keeps injectors and intake valves clean, prevents carbon deposits on valves and in combustion chambers, and helps restore and improve fuel efficiency. The product we like to recommend is Alliant Power Ultraguard Diesel Fuel Treatment or Lucas Upper Cylinder Lubricant.
Yes, we recommend replacing a rusty fuel cap. Rust particles in the fuel tank may travel into the fuel lines or injectors and cause the engine to malfunction. Rust can also invade the fuel filter and hamper fuel flow. This can result in costly repairs.