Diesel In Engine Oil Test

[fluttersmith]

I wanted to believe that the paper towel test for the presence of diesel fuel in engine oil was a quick and easy way to detect a serious problem. The presence of diesel was supposed to be detected by an expanding ring from a drop of the mix on a paper towel due to a reduction in viscosity of the oil. It continues to be touted in several forums, but this test shows the technique is without merit - it fails. The picture shows it all. There is no detectable difference in the drop samples of mix from 0% to 30% diesel in oil. :

 

[RickB]

I hadn't heard of that test, but it sounds bogus to me anyway. Two similar petrochemicals aren't going to separate that quickly or easily..........

 

[Baby Grand]

The "Bounty" test is a new one on me, too.
The "sniff" test has worked for me for gas in the oil.
Haven't had a situation (yet) where it was needed for diesel.
Keeping my finger crossed on that last one.

 

[David_Kb7uns]

Now I say try the test with used oil.

David Kb7uns

 

[Raspy]

There are a couple of ways you might get a lot of fuel into the crankcase, but it's unlikely. A bad mechanical lift pump diaphragm or injection pump seal, maybe, on others. One way you might notice it is if the oil level begins to rise rather than fall. On a good running diesel without EGR, where the oil stays relatively clean, you might begin to see a color change. Why are you concerned about it? A little diesel in the oil is not going to hurt the engine, but it should not be happening.

 

[dodge man]

I've seen the paper towel test touted also. I never knew if it worked or not but it never sounded all the great to me. I know on common rail diesel injectors can fail and get quite a bit of diesel in the oil. Also vehicles with DPF can get quite a bit of fuel in the oil from the regen process.

 

[BGigHarbor]

I am not saying the tissue test works, but one poster said paper towels doesn't work. That you need tissue paper or toilet paper - thinner and more 2 dimensional. I think a used oil might show more as well.

I am curious because my tractor has a dpf and does regens. Reportedly in some vehicles oil dilution has been tested at over 10 percent, yowser.

Another thing I've wondered about is if the folks getting lots of oil dilution can see the change in level on the dipstick.

Also thanks for the tests. You are a man after my own heart in that regard. I intend to do some seat of the pants tests myself with tissue at some point.

 

[fredws]

The only way to really know for certain is to send a sample to a lab. As little as 2% fuel dilution, and many oils will shear out of grade. At that level of dilution, the lab is the only sure way to know what is going on.

 

[art]

The most times we have seen high fuel concentrations in the oil is from running diesels cold or a leaky injector.. This normally means that the cylinder walls are glazing and oil consumption is increasing as well as loss of power. Paper towel test, doubt it is reliable as partially burnt fuel normally thickens motor oil.

 

[SPMMD]

I think this is supposed to replicate a test from medicine, trauma. After a head injury, if there was a nosebleed, a drop of the blood on filter paper or paper towel would just be red homogenous color. If CSF (cerebrospinal fluid) present, it would create a bullseye ring appearance suggesting a skull fracture with direct communication of the sinuses to the brain! Usually not a good thing!