To ensure that vehicles do not suffer adverse consequences when high-methanol-content fuel (M100 or M85) is used, it is important to understand the ways that the use of this fuel affects various vehicle systems. For that reason, some of the changes which occur in the engine oil when using methanol fuel were investigated. During a single cold start with an extended cranking time, as much as six percent fuel entered the engine oil. Over a 15-minute period, the lubricating medium changed from engine oil to an oil-methanol-water emulsion. With multiple cold starts followed by a five-minute trip and ambient temperatures near freezing, the oil contained 19 percent volatile contamination. In addition, the oil contained elevated levels of water, lead, iron, chromium, and aluminum. Efforts need to be directed toward reducing the adverse consequences of methanol fuel.