Timing & Logic for Oil Analysis

[bigmo]

New-ish 425 hour Rotax 914 (Turbo). Trying to get in a groove with my maintenance, 100 hour inspections, and annuals.

I run almost all MOGAS (more than 90%) - only the occasional long XC will I need to touch 100LL. I switched from AeroShell to Valvoline 4 Stroke Motorcycle Full Synthetic 10W-40 (which was recommended by Lockwood). Lockwood has been pretty vocal that we should run full sythetic in the 914.

My goal, if the evidence is there, is to do my oil changes at 100 hours (with my 100 hour inspection). But I want to be evidence driven, not just pick a number out of the blue.

Plan A: For logic, do I do a sample at 50? Then???

-or- Plan B: My other line of thinking was in 1/3's - so run one at 33ish. I'll presume it's good. Then another at 66ish. That 66ish should really tell me if I'm done or can indeed go to 100.

I feel the 50 is too early to predict the next half of the oil life.

Open to thoughts/suggestions.

 

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New-ish 425 hour Rotax 914 (Turbo). Trying to get in a groove with my maintenance, 100 hour inspections, and annuals.

I run almost all MOGAS (more than 90%) - only the occasional long XC will I need to touch 100LL. I switched from AeroShell to Valvoline 4 Stroke Motorcycle Full Synthetic 10W-40 (which was recommended by Lockwood). Lockwood has been pretty vocal that we should run full sythetic in the 914.

My goal, if the evidence is there, is to do my oil changes at 100 hours (with my 100 hour inspection). But I want to be evidence driven, not just pick a number out of the blue.

Plan A: For logic, do I do a sample at 50? Then???

-or- Plan B: My other line of thinking was in 1/3's - so run one at 33ish. I'll presume it's good. Then another at 66ish. That 66ish should really tell me if I'm done or can indeed go to 100.

I feel the 50 is too early to predict the next half of the oil life.

Open to thoughts/suggestions.

All I can say is I send a sample to Blackstone with every oil change. Not that expensive in the overall picture. Some say it won't help But it can't hurt. NO I do not use MMO or Camguard either. You can't go wrong with Clean oil in an engine.
But my luck varies Fixit

 

[MacCool]

I do oil analysis with every oil change. IMHO the value of oil analysis is trending and it's cheap enough to indulge the "more is better" concept relative to data points on the graph.

 

[bigmo]

Thanks guys - really sensing that instead of looking at this as a snapshot health, it's trend health. I think I'll just bite the bullet and order a 10 pack and just check them all.

 

[R100RS]

I have been flying behind a Rotax 912ULS for 1400 hours (combined across two airplanes). My planes are experimental and I do all maintenance and inspections. Although lots of 912 owners and mechanics do regular oil analysis, I have never heard a convincing reason for it. I know of no 912 engine that has ever been taken out of service for any oil analysis result that would not have been taken out of service for other reasons (e.g., excessive oil consumption, failed leak down test). So, if my engine runs well, burns no oil, and has good leak down, I don't know what value added I get from oil analysis.

BTW, it sounds like you are interested in oil analysis to assess the status of the oil (ie, when is the oil exhausted and in need of changing) as opposed to the status of the engine. Oil analysis provides some information about the oil, but not a lot. I have no idea if oil analysis is a useful indicator of when oil is exhausted to the point of needing to be changed.

In light of all this, I change the oil and filter in my 912ULS engines every 50-60 hours. I have no idea if that is too often. But, as they say, the difference between a new engine and a worn out engine is a few grams (milligrams?) of metal.