Mixing oil with fuel is a necessary procedure for the proper operation of two-stroke engines. The correct proportion of oil and gasoline ensures engine performance and its protection. If there's too much oil, it can lead to a number of negative consequences. First, the excessive amount of oil in the fuel will definitely provoke increased exhaust emissions, even if the "smokeless" oil is used. Secondly, the oil can cause poor engine start (especially at cold starts) or problems with engine operation due to the increased fuel density, so you don't want to mix too much oil. Thirdly, in some cases, with increased oil content, you may run into carbon deposit formation. All these effects are caused by excessive semi-synthetic oil concentration in fuel. The best ratio is 50/1, except for racing motorcycles.