Frequently Asked Questions About International WorkStar Fuel Tank Caps

Will these fuel tank caps fit my specific WorkStar model year?

Our International WorkStar fuel tank caps are designed to fit WorkStar models from 2008-2017. However, International made some mid-year changes to tank configurations. For 2008-2010 models, verify if you have the standard 2-inch or 2.5-inch tank opening. Models from 2011-2017 typically use the 2.5-inch standard, but we recommend checking your existing cap or consulting your VIN-specific parts diagram to ensure proper fitment.

What's the difference between locking and non-locking caps, and which should I choose?

Locking caps feature a key mechanism that prevents fuel theft and tampering, making them essential for trucks parked in unsecured areas or left unattended for extended periods. Non-locking caps offer easier daily access and are typically 30-40% less expensive. Most fleet operators choose locking caps for added security, while owner-operators who park in secured locations often prefer the convenience of non-locking versions. Both types maintain the same seal quality and pressure ratings.

Are these caps vented or non-vented, and why does it matter?

Most WorkStar models require vented fuel caps to prevent vacuum buildup in the tank as fuel is consumed. Using a non-vented cap on a system designed for vented caps can cause fuel pump strain, poor engine performance, and difficulty removing the cap. Check your original cap for vent holes around the seal area or look for "VENTED" stamped on the cap. When in doubt, choose vented caps as they're compatible with most WorkStar fuel systems.

How do I install a new fuel cap without damaging the tank threads?

Start by cleaning the tank opening threads with a wire brush to remove any dirt or corrosion. Apply a small amount of diesel fuel or light oil to the cap's O-ring seal before installation. Thread the cap on by hand, turning counterclockwise first until you feel it drop slightly, indicating the threads are aligned. Then turn clockwise until snug - typically 1/4 turn past the gasket contact point. Never use tools to tighten, as overtightening can damage the seal and make future removal difficult.

What material holds up best against diesel fuel and weather exposure?

Look for caps made from reinforced polymer or aluminum construction. Polymer caps with UV inhibitors resist cracking and fading better than basic plastic versions, typically lasting 5-7 years in normal use. Aluminum caps offer superior durability and can last 10+ years but cost approximately twice as much. Both materials should feature Viton or EPDM O-ring seals rather than standard rubber, as these materials resist diesel fuel degradation and maintain flexibility in extreme temperatures from -40?F to 250?F.