Value of oil analysis

[RobertE]

Best practice, of course, is to use oil analysis and cut open the filter with each oil change. I do the later, but not the former. Is there anyone who identified a problem and took an expensive action (say, an engine tear down) solely because of the results of oil analysis, and that action was appropriate? In the vast majority of cases the response seems to be "keep an eye on it". If there are some success stories, though, perhaps I should change my routine.

[kris_adams]

I'm with Jim on this one. I did oil analysis right up until my MOH last year. It didn't show us anything and certainly didn't make me think I was about to major the engine. I'm part of the cut and inspect club now.

[PTK]

Oil analysis in addition to cutting filter each and every oil change. They are mutually exclusive since they look at different things. Oil analysis looks at microscopic particles that will never be seen in the oil filter. Oil filter will trap larger macroscopic pieces of metal and will never show microscopic wear. Regular oil analyses enable you to see and establish historical trends for the engine as they are developing. Also it will show departures from the trend very clearly. It's an early warning system! I think this is very valuable and cannot be done by simply cutting filter. I like to have as much info as possible! Ymmv.

[Bartman]

I have seen where people have done engine overhaul based on calendar time, engine time, some change in performance, or material in the filter. I don't recall having seen anyone tear an engine down based on oil analysis. However, i do remember reading where owners have done an engine teardown and then after looking at the findings make a correlation to historical oil analysis data.

I dont have any statistics to back this up, but I think oil analysis would have a high false positive and a high false negative rate and therefore unreliable to make a $25,000 decision. I see it as something to worry about for the owner. It does provide jobs for Blackstone, but have NEVER seen anyone who says the lab recommended an engine teardown.

[Cruiser]

Just one more tool in the toolbox. Oil analysis combined with other indicators can tip you off to problems earlier than otherwise (or never) being detected.

I would bet that oil analysis has helped prevent damage that might have occurred rather than trigger overhauls.

[garytex]

I have seen high silicone readings get folks to find and cure airbox leaks letting sand in and maybe dodge an early top. And high aluminum leading folks to wrist pin end cap galling. And high copper to rocker shaft bushing wear. I think that it is good info to have every 100-200 hrs.

Gary

[jwilkins]

1980 M20K: less than 500 SMOH. My oil analysis started showing an increase in iron. We didn't know why. The lab suggested perhaps a lack of flying from the previous owner, but that didn't make sense with the previous analysis and my flying times since purchase. Resampled in 25 instead of 50 showed another slight increase. Meanwhile the alternator (direct drive) began to take several minutes to come on line after sitting over night. The shop said 'probably not related, most likely the coupling is slipping, but let's pull the alternator to check it out'. The direct drive coupling had been improperly installed by a previous mechanic and was slowly grinding up the alternator shaft. The coupling and alternator were replaced; the oil analysis came down to normal.

Bottom line: the oil analysis MAY show when something is not normal. The problem is figuring out exactly WHAT is not normal. There are a lot of 'this typically indicates ...' but the oil analysis does not produce a diagnostic, just a symptom. I do it every oil change. It's an additional data point to consider when you are putting together all the facts. When an overhaul costs more than the first house my wife and I bought, $25 is a pretty inexpensive charge to get one more data point. I'm happy when I see 'all normal' and think it's worth the cost to get one more data point, whether that data point is good, bad, or just plain confusing.

Jim

[mikefox]

We use both oil analysis and filter inspection. Can never have too much information. Goes along with listening to the airplane, too. Friend of mine had a very subtle periodic vibration go though his airframe, along with increasing oil consumption, though not tremendous. He tore into it and found a broken ring on one piston! No pieces in oil filter (too big - probably sitting in bottom of sump) and nothing on oil analysis.

[BigTex]

I'm in the oil analysis and cutting the oil filter camp. The way I see it, I need as many data points as possible when it comes to evaluating the health of my engine.