Fuel in oil test - DIY w/ baseline results.


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Jan 10, 2020
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Knoxville, TN
2019 Ford Ranger - 2010 Ford Ranger
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Started reading a bit and discovered an at home test that could ease some worrying minds. While not entirely scientifically accurate, with as much fuel dilution that other members are claiming they have - this should easily show some form of evidence.

You want to place a drop or two of used oil on the surface of chromatography paper (good heavy white card stock works pretty well too). Lay the paper or business card flat, but so that all but the very edges of the paper is suspended. For a fairly stiff business card, placing two pencils down on a table and laying the business card so that the ends are resting on the pencils would work well.

You want to wait for the paper or card to absorb the oil drop(s) which might take awhile. Once all of the oil has been drawn into the pores of the paper you can begin evaluating the condition of your oil.

A colorless spot or slight yellow outer ring - "good" oil.
A dense, dark deposit zone - Dispersancy failure
A black, pasty zone - Glycol (Antifreeze) in your oil
A dark center with distinct outer ring - Severely oxidized oil
A dark center with surrounding rings - Fuel in oil
Information for the blotter spot test can be found in:
Fitch, J.C., "The Lubrication Field Test and Inspection Guide" Noria Corporation 2000

Here is a PDF for the test.

Please post any pictures! Also, 24 hours is sort of the safe zone. With 5w-30 I would imagine 2 hours being fine.