WIX Fuel (Complete In-Line) Filter. Filtration is the foundation of an effective maintenance program helping equipment remain closer to new condition for a longer period of time. Filtration is more than filters. WIX supplemental items include bases connectors installation aides air filter wraps bowls supplemental additives pressure gages and test kits. These items aid filter installation extend useful service life or provide data to assist in determining effective service life. Case-IHC Equipment - In-Line style.