Microscope for engine oil analysis

[PeteM]

That BHM is a wonderful scope. For transmitted work, the nosepiece and objectives and the vertical illuminator could be moved to an Olympus BHT or BHS stand.

[Niklas]

Wow, that is interesting.

Can you maybe pull some oil from a dip stick and see if it will work for my purpose?

[mrsonchus]

Hi Niklas, I can try! Can you give me a better idea of what I need to be doing?

[Niklas]

From my understanding you could just put a drop on a glass slide and put a coverglass on top to spread it.
You are looking for particles in the size of roughly 5-15um (some larger, some smaller) which are suspended in the oil. See if you can take a picture where they are visible. The soot (which makes the oil black) are in nm scale and probably will not show up other than as a color of the oil.

I would like to see if it is possible to take a picture of them (for use in image software) and also if you are able to see the structure(flat/round/curved etc).

[MicroBob]

Hi Niklas,
one criteria to identify the metals will be the colour of the reflected light. So it probably will be necessary to wash the murky oil away to keep it from staining the image. One problem can be that particles can look very different depending on oxydation of the surface. Steel particles could even be couloured when they have reached more than about 400°C. So a reflected light microscope would give you more information than a transmitted light microscope. Having reflected bright field as well as dark field is another valuable option. To get a better feeling for the look of differnt particles you might apply the cleaned wear particles onto a grid that allows to locate the particles repeatedly. An investigation with a SEM with EDAX scanner would give you the chemical elements that are contained in the metal wear particles . Attatched you can see the result of an EDAX scan or a silver brazed area of a metal part. The area can be chosen very small. This was made at our university. For professional application you should see that the SEM Lab has experience with metal and can calibrate the EDAX scanner properly.

BTW: Among my many microscope samples that await to be processed there is the oil filter sludge of my 1974 Honda CB250. It has a centrifulgal oil filter that delivers a nicely concentrated wear particle mass.

Bob

[mrsonchus]

Hi again, here's a series of calibration images taken with the Toupcam to use for particle measuremens,


A selection of images taken this morning, after collecting a little oil as suggested from the dipstick of my car and coverslipped to slide for imaging...

The sample,


The slide,


The Toupcam 5mp,


5x objective BF transmitted,

Darkfield same objective,



10x objective BF and DF,

and


20x BF and DF,

and


50x BF and DF,

and


Hope these give an idea for your project.

[75RR]

That makes it official, time to sell the sedan before the engine gives up the ghost and buy a sports car!

[MicroBob]

Car engines have filters in the main oil stream, so there should be no particles in the oil above a certain size. A lawn mower might provide interesting samples as they don't have an oil filter at all.

[Niklas]

I visited my father in law this weekend and turns out he had a microscope to borrow me:
http://www.paralux.fr/donnees/documents ... 6113-9.pdf

Very simple(mechanics feel really solid and precise) but it's good enough to see the amount of particles in the oil (40x objective 16xeyepiece). I'll start with this and see what I can do.

[BramHuntingNematodes]

i like that brochure "Stereomicroscope. Type: not stereo"

[EYE C U]

if your oil looks like pearl black paint you have an issue.

[PeteM]

Bob - what a fantastic presentation. Almost makes me want to mow the lawn, then check the oil . . .

[MicroBob]

Hi Pete,
the graph shows the analysis of a silver brazed steel part, I made for a group meeting on the material steel and materials science methods and had these graphs made at our university. I like measuring instruments a lot and would enjoy to have a SEM with EDAX scanner, but this is just overkill for home use, involved cost apart. Just today a use appeared: I bought planer knives for my jointer and thickness planer (for woodworking), sold as HSS steel. The sparks they give of when held to a grinder say they are high carbon steel, not HSS - honesty is a rare good today!

Bob

[PeteM]

I was wondering about all that copper, silver, and cadmium . . . .

There are a few more tools I'd like to have as well - but seems my dear wife doesn't think we need either a backhoe or an XRF spectrometer. I did buy up 1/2" diameter rods of a dozen grades of steel to use for spark test comparisons . . .