Cessna 120-140 Association

Did that yesterday. If the oil tank is equipped with a quick drain, I drain approximately a quart of oil off then gather a small sample that's coming out of the drain in the sample bottle. On the other hand, if the oil tank has the original type plug, after removal let a small amount drain off then catch a sample. I never take oil out of the drain pan for the sample, too much chance for contamination. Suggest you wear nitrile gloves, and don't drop the sample bottle. Just my 2 cents.

They recommend that you use the same procedure each time for consistancy.
Example: After flying it to get it warm (it also help to drain the oil faster) and for the particles that they are looking for to be in suspension.
Let some drain off like 6183 suggested before collecting a sample.
For best results remember is to do it every time to get a trend going.

Rick

Catch it in a clean bottle from the stream of oil coming out of the sump drain. Try to get it about midway through the process.

I change my oil about every 25 hours or so (I have a filter) if for no other reason but to keep the lead contamination down. I used to do an oil analysis every oil change but now only do it once a year.

I found that the amount of lead in solution in the oil is a function of time. More time between changes, more lead. I have test data from Blackstone that clearly shows this. By changing the oil more frequently, the theory is that there will be less lead in solution in the oil and less potential for deposits of lead in the valve guides. I may be right…or I may be wrong on this, but that is my thinking. I had a stuck vale issue about 12 years ago that could have need up much worse than it did…my preference is to not go through that again. So far so good.

I also change my oil every 25 hours, and i too have/had a stuck valve. From watching the video below the culprit appears to be lead bromide (a byproduct of combustion) which when a cylinder is not running hot enough, sticks to the cooler lower exhaust valve stem/guide. Since i don't fly much above 5000' i don't lean which is the cure to prevent stuck valves -lean it and get everything in the head hot so the burned gasses blow out the exhaust and don't collect on the stem/guide. I also run TCP (lead scavenger) but that doesn't help with stuck valves. As soon as i have it back up in the air will try to lean it below 5000' which is a departure from what i've been doing. Here's a good video to watch about why valves stick if you're interested: https://www.youtube.com/watch?v=7ohsVvYbAaQ. For what it's worth my cylinder didn't have "morning sickness," simply started with the exhaust valve stuck open -the guide and stem are seized tight.