A valve cover includes a base that attaches to an engine and a display window that attaches to the base. The display window is made of material that can withstand the operating environment of the engine, including temperature and resistance to petroleum-based substances. The display window is secured to the base using a flexible gasket that encircles the display window and snaps into a groove in the base to secure the display window to the base. The display window may be see-through so the valves are visible. The display window may also include one or more display elements, such as light-emitting diodes, optical fibers, electro-luminescent panels, incandescent bulbs, liquid crystal displays, etc. The display window may include embossed or etched portions, and may include multiple colors and sequenced operation to provide any desired effect on the display panel.