elevated aluminum on 300 hr 912ULS

Alan,

First of all, what did the lab report say about it?  Blackstone Labs indicates the universal average for aluminum is 4 PPM with a 40 hour oil change interval. That can be extrapolated as 1 PPM for each 10 hours of operation, so 10 PPM at 100 hours would be the average.  So you are double that average and I would want to know why this changed.  

Did you cut and inspect the filter?
Are other wear metals high also or just aluminum?

last aluminum was 8.4

filter was normal

no other abnormalities except aluminum.

Alan

Hi Alan,

"filter was normal"

Does this mean, that there was no significant evidence of metal in the filter medium? 😈

no metal on visual inspection

No metal in the oil filter but high aluminum in oil sample. The pistons are the biggest source of aluminum.  Preignition and piston skirt scuffing can raise the aluminum in an oil sample. You could look at the cylinders and piston tops with a bore scope but the scuffing could be below where you can see with the piston in the way. This is common on certain horizontally opposed automotive engines, in which case you pull the oil pan and look from the bottom with the piston at TDC. Not possible with a Rotax engine with no oil pan. Here are some things you can do fairly easily.   

Make sure you are using a good fuel with the proper octane rating, and follow the Rotax guidelines for manifold pressure and RPM for the octane of the fuel you are using. Loading the engine too heavily can promote pre-ignition. 

Fully drain the oil system, oil cooler and oil lines. Put in new oil and purge. Then send another sample at 10 hours and hope for about 1-PPM at that interval. Reduce your oil change intervals to 25-50 hours. 

Do a differential compression test if you have not already, and look for a suspect cylinder.  

Bore scope from the spark plug holes and look for signs of piston scuffing. Not fool proof, but it’s better than not doing it.

The oil pump itself can make aluminum, but that more likely shows up in the filter as visible particles.