Stihl MS 311 Product Instruction Manual - Page 27

Fuel This engine is certified to operate on unleaded gasoline and the STIHL twostroke engine oil at a mix ratio of 50:1. Your engine requires a mixture of highquality gasoline and quality two-stroke air cooled engine oil. Use mid-grade unleaded gasoline with a minimum octane rating of 89 (R+M/2). If the octane rating of the mid-grade gasoline in your area is lower, use premium unleaded fuel. Fuel with a lower octane rating may increase engine temperatures. This, in turn, increases the risk of piston seizure and damage to the engine. The chemical composition of the fuel is also important. Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but magnesium castings and catalytic converters as well. This could cause running problems or even damage the engine. For this reason STIHL recommends that you use only nationally recognized high-quality unleaded gasoline! Use only STIHL two-stroke engine oil or equivalent high-quality two-stroke engine oils that are designed for use only in air cooled two-cycle engines. We recommend STIHL 50:1 two-stroke engine oil since it is specially formulated for use in STIHL engines. Do not use BIA or TCW rated (twostroke water cooled) mix oils or other mix oils that state they are for use in both water cooled and air cooled engines (e.g., outboard motors, snowmobiles, chain saws, mopeds, etc.). Take care when handling gasoline. Avoid direct contact with the skin and avoid inhaling fuel vapor. When filling at the pump, first remove the canister from your vehicle and place the canister on the ground before filling. Do not fill fuel canisters that are sitting in or on a vehicle. The canister should be kept tightly closed in order to avoid any moisture getting into the mixture. The machine's fuel tank and the canister in which fuel mix is stored should be cleaned as necessary. Fuel mix ages Only mix sufficient fuel for a few days work, not to exceed 3 months of storage. Store in approved fuel-canisters only. When mixing, pour oil into the canister first, and then add gasoline. Close the canister and shake it vigorously by hand to ensure proper mixing of the oil with the fuel. Gasoline Oil (STIHL 50:1 or equivalent high-quality oils) US gal. 1 2 1/2 5 US fl.oz 2.6 6.4 12.8 Dispose of empty mixing-oil canisters only at authorized disposal locations. Fueling Preparations English 001BA159 KN N Before fueling, clean the filler cap and the area around it to ensure that no dirt falls into the tank. Always thoroughly shake the mixture in the canister before fueling your machine. N Position the machine so that the filler cap is facing up. In order to reduce the risk of burns or other personal injury from escaping gas vapor and fumes, remove the fuel filler cap carefully so as to allow any pressure buildup in the tank to release slowly. MS 311, MS 391 25