What size is the washer on the filler plug of rear diff on a Honda HRV?

These fill washers are also commonly known as crush washers. Because each are designed toÊhave spring-like properties so that when the bolt is screwed in, the washer pushes out on it to create a tight fit. Hence, these washers are usually discarded after each use. The size of the washer for the fill plug of the rear differential is usually 20 mm.