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.
Recognizing the different models is easy: the 912 has black cylinder covers, the 912S green/blue (blue for the french market) and the 914 has red covers and a turbo. These are the most obvious differences.
SB-912-043-914-029, Coolant Specification
Excerpt from the document:
Using conventional coolant with a mixing ratio of 50% coolant and 50% water may cause in some applications boiling of the coolant before reaching the max. allowable cylinder head temperature. On all affected engines the following changes have to be considered and accomplished (if applicable).
Change of coolant specification, change of the cylinder head temperature limits, introduction of a new coolant temperature limit and the requirement to measure and monitor this parameter, change of radiator cap.
To continue reading see the pdf below: