Typical oil capacity of a 2015 Harley-Davidson motorcycle is between 3 and 4 quarts of oil. However, oil capacities of Harley-Davidson motorcycle engines vary between models, trims and production years.
As a general rule, larger Harley-Davidson motorcycles and larger engines require more oil to function. For example, the 53.9-cubic-inch Evolution engine used in the 2015 Sportster SuperLow bike has a 2.8-quart oil capacity. In contrast, the much larger Road Glide Special touring bike has a larger 103.1-cubic-inch engine and an oil capacity of 4 quarts. Though the smaller 2015 Street Bob motorcycle uses essentially the same engine, its oil capacity is only 3 quarts, largely due to the absence of the integrated oil cooler used on the Road Glide Special.