Abstract: An optical sensor for detecting a level of a liquid in a reservoir, the optical sensor including: a display; a light pipe optically connected to the display and extending to a level of interest in the reservoir, where the light pipe is formed from a material having a refractive index higher than air's refractive index and less than or equal to the liquid's refractive index; and a light optically connected to the light pipe. The term “light pipe” as used herein is intended to refer to a glass rod, a plastic rod, or an optical fiber, a bundle of optical fibers, or the like.

Abstract: A seal within the filler neck of a fluid reservoir is configured to provide fluid channels into the reservior while in the at-rest position, but seals the filler neck when deformed by an externally directed insert in the filler neck. The seal is a hollow bulb with a frusto-conical surface spaced from a parallel frusto-conical surface of the filler neck by a plurality of ribs therebetween. The gap between the ribs, and between the surfaces of the seal and the filler neck, from fluid channels for replenishing the reservoir. A plunger inserted into the filler neck deflects the seal outwardly into contact with the filler neck, closing the fluid channels and preventing matter from entering the fluid reservoir.