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on a limited basis but the lead in this is not good for the engine and additional precautions/procedures should be researched for the particular make/model of engine for primary use. 

Always use a higher grade/octane of fuel rather than a lower grade, or detonation will severely damage the engine in a very short period of time. Check the aircraft operation manual and the engine manual for the type of fuel to use. 

When attempting to fuel for maximum capacity, remember that many fuel tanks are very sensitive to attitude. Fill the aircraft on a level surface and check to ensure the amount of fuel in the tanks is adequate for the planned flight plus 30 minutes of reserve. Check the level in the fuel tank plus the panel-mounted gauge, if so equipped. 

To transport gasoline, clear gas cans are preferable because the fuel is visible through the container and allows a pilot to look at the container for fuel level. [Figure 5-59] 

An important step in any preflight is to check for water and other sediment contamination. Avgas is more probable to have water in the fuel tanks because auto gas typically has alcohol in it to boost the octane. Alcohol absorbs water, running it harmlessly through the system. 

When using 100LL Avgas, water tends to accumulate in fuel tanks from condensation, particularly in partially fi lled tanks. Because water is heavier than fuel, it tends to collect in the low points of the fuel system. If Avgas is used, drain any water from the low point in the system. 

##  Oil 

A four-stroke engine’s oil level should be checked during each preflight and rechecked with each refueling. Four- stroke engines can be expected to consume a small amount 

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of oil during normal operation. If consumption grows or suddenly changes, qualified maintenance personnel should investigate. 

If the Rotax 912 oil level is low when the oil is checked, rotate the propeller in the correct direction (counterclockwise, facing it) to pump any oil from the engine back into the oil tank for a proper measurement and recheck oil level before adding oil. [Figure 5-60] 

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Check the reservoir level of two-stroke engines with oil injection at each gas fill-up. It is also very important to ensure the oil reservoir has clear air vent holes to allow continuous flow of oil to lubricate the engine. Always use the same type of oil because different types of oil harden and stop the oil injection process, resulting in a seized engine. Additionally, 

