Oil Change Screwup

I'm with Bill.

He makes a good point and I don't think it caused any major issue.

The Rotax instruction says turn by hand to purge, don't crank with the starter. It's unusual to see the experts on here going against Rotax - why in this case?

I've done it a couple of times, without pressurising the tank, it did take a lot of turns!

quote SI-912-018R2

NOTE :Do not use the starter for this purpose. Fit propeller and use it to turn the engine

and

Turn the engine by hand in direction of normal rotation until the first pressure indication on the oil pressure gauge of engine instrumentation in the cockpit. Normally this will take approx. 20 turns. Depending on installation it may take up to 60 turns.

I find that by blocking the return inlet to the oil tank and pressurising the tank via the vent hose using a car foot pump expedites the process.

I guess that cranking on the starter is likely to generate more frictional losses in the engine if there is a lack of oil pressure and this may damage some of the bearing surfaces. It seems unlikely to be a problem if the engine has already had oil circulating but I guess that Rotax need to give advice based on all possible scenarios, including a dry or freshly rebuilt engine.

After filling the tank (2.5L) I turned the prop by hand about 22 times.  I then started the engine and carefully watched (and video'ed) the oil pressure.  It came up to normal pressure in less than 5 seconds, so I felt good about that.

I ran it to the operating range, shut it down, burped the engine, checked the level (min) and topped off the oil tank with the remaining .5L as it needed it to get above the halfway point on the dipstick.

Went flying last night and all is well!

Thanks for all the advice!