Antifreeze trace in oil analysis

Where did you send your oil sample for testing? This is very unusual, as there should be no situation where coolant mixes with oil. Rotax engines do not have a head gasket like those in automotive engines. The cooling system is entirely sealed and isolated within the cylinder heads, coolant hoses, radiator, and water pump.

There are three possible explanations for this:

• A contaminated oil sample.
• Someone accidentally added coolant to the oil tank.
• (Extremely unlikely) The cylinder head has a porous casting, allowing coolant to enter the combustion chamber. However, this would have shown up in previous samples, and we can't recall a situation where this has happened.

Our suggestion is to send in another sample for testing. If the results again indicate the presence of coolant in the oil, we recommend the following:

• Inspect the combustion chamber with a borescope.
• Check the spark plugs for anything unusual.
• Inspect the cooling system for leaks or evidence of low coolant levels.
• Perform a coolant pressure test to 17.4 PSI (1.2 Bar).
• Conduct a cold compression leak-down test with the coolant cap open and check for air bubbles.

Feel free to reach out if you have any questions.

Thank you, All your reasoning/explanation is very helpful! 
I’ll send in another sample to a different oil analysis site. 

Any "connection" between combustion chamber & coolant system, is usually accompanied by very high coolant temperatures and loss of coolant - seems very unlikly.

Yes, coolant temp and quality constant. 

Do you use the same funnel to add coolant and oil?