Rotax four stroke aircraft engines have proven themselves as reliable pieces of machinery. They can be bought as experimental (UL) or certified (A and F) engine and there are four main models (injected too) to date. The original engine is the 80 hp 912, from which the 100 hp 912S was developed and Rotax also has a 115 hp turbocharged 914 engine. In 2015 Rotax announced the 135 hp fuel injected turbocharged 915iS.
Not using the correct operatings fluids in these engines is a safety issue. This service instruction describes criteria for proper oil selection based on the fuel type that is used, operating conditions and flight profile. Guidance is also given for the selection of the correct coolant: the operator has the choice of using conventional 50% mixture or a waterless coolant.
SI-912-016-914-019-R5, Operating Fluids
Excerpt from the document:
Field experience has shown that additional information about the choice of suitable operating fluids, such as motor oil, coolant and fuel, and about oil change and maintenance intervals for ROTAX® engine types 912 and 914 is necessary.
Selection of suitable operating fluids for ROTAX® engine type 912 and 914 (Series). This information should help the aircraft builder and operator ensure that the operating conditions and installation are correct and thereby achieve optimum performance and reliability.
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