oil analysis results

oil analysis results

<HTML>I have had a problem with abnormal oil analysis on an ongoing basis, and my A&P really does not have a plan of action for this.
I bought the airplane with a 0 hour factory remnan, The first analysis (Sept. 1999) was normal.

At the 100 hours TT, 50 hour oil change, analysis was done by CTC. Wear metals were reported high, Possibly normal break-in:
Iron: 122, Chromium 29, Aluminium 28, Nickel 29.

At an oil change 27 hours later, values were again normal

50 hours later, at 205 hours TT on the engine, the techs forgot to get a sample and got one by squeezing out oil from the filter. That sample was abnormal with wear metals high suggesting possible cylinder wear and piston scuffing. Silicon was also high and they suggested inductiion system inspection. The induction system was normal. No metal chips were found in the filter. 
Iron: 230, Chromium 21, Aluminium 39, Nickel 35 silicon 26.

the next oil analysis was skipped..

My shop then changed labs, to AOA in Phoenix
Analysis was done at an oil change at 47 hours (253 hours):
Iron: 229, Chromium 21, Aluminium 31, Nickel 54 silicon 15 (normal).
Again the suggestion was to repeat the sample.

My last analysis is just completed and is again abnormal, with no chips in the filter, and interpreted as possible cylinder/valve guide wear. Engine time is 310 hours.
Iron: 150, Chromium 13, Aluminium 23, Nickel 26 silicon 14.

My mechanic want to repeat the sample at 15 mor hours, but when asked is not sure what to do if the values are still high.

Can you help?
The engine is on TCM's Top Care program.
It is usually flown at least once a week. It has been on several long trips including the east coast, florida, texas and California.
I use an engine analyizer. I lean to 50 degrees rich of peak as limited by the CHT's. I keep the CHT's always below 450 and I try to keep them under 400.


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Re: oil analysis results

<HTML>Firstly, it is counter-productive to change sample analysis laboratories and expect to have valid data.  You MUST choose and stay with the same laboratory, or at least have 3 or more analysis's performed by the same shop prior to forming an opinon on the trend/wear patterns.  Next, you MUST ALWAYS take the sample in the same fashion, i.e., from the oil while it is draining, and preferably in the middle of the drain, not the first out of the sump nor the last.  (NEVER from the filter, because the job of the filter is to catch dirt (silicon) and metal, which will skew your results inappropriately.)  Basically, the methods and techniques you are currently describing are a simple waste of your money and time.  The single most important factor in oil analysis is consistency.  Do it the same way, at the same time between samplings, using the same laboratory,...or don't do it at all and simply cut open your filter and look for metal particles.  (I subscribe to the last suggestion, and save my money for frequent oil changes and overhauls.)</HTML>

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