Diesel Fuel in Engine Oil Paper Towel Test - It Fails

[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 oi

 

[alrman]

Try doing the same test with warm sump oil. I've used this method for 30yrs - I've got no problem with it.

 

[JBGASH]

alrman, what do you mean by sump oil? Thanks

 

[Nige]

alrman, what do you mean by sump oil? Thanks

Oil drained from the oil pan (the sump to us Brits & Aussies). In other words do the test when the oil is at normal operating temperature, not ambient temperature.

 

[CAT793]

I trust it when making calls on $8 mill. LOHT so I see no reason for you not to trust it.

Few comments:- a piece of A4 paper is more accurate. The oil has to be SOOT loaded. New Engines on New Oil it is far less accurate due to the similarities Diesel and DEO only being a few carbon Atoms different. And certain oils that use a cheap low end base stock of oil can throw larger silver ring ( can be a good indicator to an oils base stock quality). As Nigel indicated temperature is key. I am fairly confident I can also tell just observing the oil drip off the end of a Dip Stick (Viscosity Drop and surface tension) though I would verify this with another test.

 

[JBGASH]

Nige, thanks for explaining that to me, makes sense now, just never heard a pan called that before.

Oil drained from the oil pan (the sump to us Brits & Aussies). In other words do the test when the oil is at normal operating temperature, not ambient temperature.

 

[Nige]

For our US members, what Cat793 is alluding to is to use regular paper out of your printer as opposed to absorbent kitchen paper.

Good point about the oil being well used. New oil doesn't throw up anywhere near the differences, and it looks to me in the photo the OP posted that the oil he used for the test was new.

 

[alrman]

Well there ya go, I always thought Brits called a sump "the crankcase" - ya learn somthin' new every day! :naughty

Is there no A4 paper in the US?

 

[mitch504]

A4 is listed as a smaller size you can use on my printer, but I don't think I've ever seen any. We use 8.5 x 11 inch for most things here.

 

[Nige]

Well there ya go, I always thought Brits called a sump "the crankcase" - ya learn somthin' new every day! :naughty

Don't know about the rest of the Brits but to me the crankcase is the hollow space inside the cylinder block from the bottom of the pistons down to and including the crank. The sump is what bolts on underneath the crankcase and holds the engine oil.................

A4 is listed as a smaller size you can use on my printer, but I don't think I've ever seen any. We use 8.5 x 11 inch for most things here.

Not much difference size-wise between the two TBH. A4 measures 8.4" x 11.7" and is the standard paper size commonly found everywhere in the World apart from North America.

 

[mitch504]

Don't know about the rest of the Brits but to me the crankcase is the hollow space inside the cylinder block from the bottom of the pistons down to and including the crank. The sump is what bolts on underneath the crankcase and holds the engine oil.......

Uhh uhh, that's the oil pan.
The sump is a hole in your basement floor that a sump pump goes in.

 

[Nige]

I bet you call the windscreen on your car a windshield doncha ...........?? :tong

 

[mitch504]

Of course, if it was a screen it would just keep the bugs out, the 60 mph wind would still make my eyes water....

 

[mitch504]

To be honest, the sump here is the low spot in the oil pan where the pickup tube is.

 

[fluttersmith]

OK, thanks for the comments. To address ALRMAN's concern about temperature, I repeated the 0 and 30% diesel tests at 150 Deg F (attached). Again no difference in the samples with and without diesel. CAT793 may have a point about used oil, "soot loaded" - perhaps there is a chemical presence in well-used motor oil that will produce a real difference with diesel. Another test?

 

[Nige]

It appears as though you are using absorbent kitchen paper in that 2nd photo..? If so it won't give as good an indication as using simple plain paper out of your printer. Even so to me the circle with the diesel-contaminated oil appears to be larger than the one without, it may be just a trick of the photo.

As mentioned by quite a few posters above. This test only works with engine oil that has worked a fair few hours and that contains significant amounts of soot. Let's face it if you suspect that an engine has an internal fuel leak into the oil then you would use a sample of the oil from the engine for the test, not new oil.

 

[Scrub Puller]

Yair . . . Dunno. According to my callipers on my monitor there is about five mill. difference in those blot sizes.

We used to use plain old newsprint and, as I have mentioned here before, I always found racing the oil drops down an inclined plane of glass more convincing.

I think I have mentioned a bloke I knew who, if possible would not own a diesel engine with injectors under the tappet cover. He reckoned it eliminated most of the risk of unnoticed oil dilution.

Cheers.

 

[mitch504]

Yeah, I've always thought it was safer having them outside, too.

 

[cumminsdude]

I know this treads kinda died out but I tried this test today and got a pretty good result the diesel ring was visible within less than a minute and the separate sample I tested without diesel showed no signs of a ring whatsoever I used regular printer paper and both oils had been run in equipment. I definitely think you should give this test another shot but with used oil. I will retry the test again and try to post some pics because my control sample with no diesel was actually out of a gas motor since it was the closest machine. I'm not saying this is an entirely accurate test since there's no way of actually knowing the amount of dilution but I do think it can reliably tell you if there is a high concentration