Oil Analysis

[lbgjb]

During Phase I testing and using mineral oil, is it recc to do oil analysis?? Any recc for good companies for analysis. thanks. lbb

[Geico266]

The readings are gonna be all over the place on the 1st oil change. Wait til you change out this oil with whatever you are gonna run and then get your baseline readings next oil change.

[Steve Sampson]

I have used Blackstone for many years and been very happy.

[Low Pass]

Going to have to trend the analysis to look for progressive degradation. Also need to runwith the same oil (understanding the need to run straight mineral oil early), same process, same lab, at the same run time between tests to get meaningful trending.

If you've got a brand new or freshly overhauled engine, be looking for metal in the screen and filter the first few cycles.

I use Southwest Spectrochem Labs in South Houston, TX for aviation and industrial work.

[RScott]

Aviation Consumer rated Blackstone as the best.

[mistergerf]

Blackstone gets my vote. For $20 its money well spent. Personally I do it at every oil change. At my last oil change I switched out the rocker cover gaskets for the silicone type. At the next analysis I got an urgent note from them - "your silicone levels are high !!" Obviously they ARE watching. But don't obsess on the absolute numbers - its all about trends over time. If something changes, there's a cause - find the cause, even if its only to eliminate it as a concern.

[rocketbob]

I lost a bit of faith in oil analysis recently. On an airplane I maintain I cut open the filter and pulled the screen...they were both full of small flakes of trash (aluminum), maybe .005" or so in size. Out of curiosity we sent the oil off to Blackstone to get analyzed just to see what would show up. It came back good. In the mean time a bit of investigating revealed the magneto drive gear bearing which is only used on the IO-360's and 540's seized and trashed the bore where the it fits into the case, and of course the bearing disintegrated. I pulled a cylinder which was running low on compression and when I did...the rings fell on the floor in pieces. Looked inside the case and saw lots of evidence of pieces floating around the crankcase... needless to say I'm overhauling the engine now.

When I inspect filter pleats I normally take the filter media out of the can, cut it into two pieces, fold them back up flat, and put it in a vise to squeeze the oil out. Works like a champ, and if I didn't do that in this case, I don't think I would have seen the trash in the filter. You can't see trash in the filter if there's oil covering it up. In this case if we went off of the oil analysis and did a cursory inspection of the oil filter its very possible that something bad could have happened.

[RScott]

Rocketbob & others who are disillusioned with oil analysis,

Oil analysis won't and isn't designed to detect the kind of problem Rocketbob found. If you can see the particle, it's too large for OA to see it. The smallest particle the human eye can see is usually around 40 microns under good light conditions; OA looks at particles around 8 microns and smaller.

OA finds microscopic particles that rub off parts as they wear. If wear increases abnormally, so will the OA reading. That's why the trend is the thing with OA; you're looking at changes from one sample to the next. Disintegration, catastrophic failures don't count.

[mistergerf]

The original question was specifically about OA - but these are all good points. I also cut open the filter, pull out all the paper and rinse it in a bucket of mineral spirit. I evaporate the mineral spirit till its almost all gone and then run a magnet around in the residue to see if it picks up any ferrous debris. Then I evaporate what's left and check the residue to make sure its no more than flakes of carbon. There's a whole recipe of things you can do with the residue to detect what kind metal it is - but for me that's going over the top.

Oil analysis is just one of the tools in your toolbox - its not foolproof, but its useful. A regular check on the oil screen is also important

[Mike Armstrong]

Hi Larry, here's an EAA video on the subject.

http://link.brightcove.com/services/...ctid1672104239


Mike