oil sample question...

[Scot]

Is it possible for fuel levels in oil to lower over a couple thousand miles. I had a 12.5K sample that came back with 4.5% Just to make sure the test was accurate I sent in another one 2K later when I changed the oil. The later sample came back at 2.5%

There was no oil added during that time so I didn't dilute it down. What could lower the fuel ratio in a "closed" system? Should this margain of error just be expected with testing???

 

[CHPMustang]

Is it possible for fuel levels in oil to lower over a couple thousand miles. I had a 12.5K sample that came back with 4.5% Just to make sure the test was accurate I sent in another one 2K later when I changed the oil. The later sample came back at 2.5%

There was no oil added during that time so I didn't dilute it down. What could lower the fuel ratio in a "closed" system? Should this margain of error just be expected with testing???

If you added any fuel additive to the fuel during that course of the oil,it's known that some of the properties of the additives can make it by the O-rings/Piston Rings to the oil thus raising the % number more than by fuel alone.

I have 4,800 mile sample that goes out in the morning to Blackstone

 

[LA350]

What was driving the test for fuel? Was your viscosity down in your oil? If you are adding additives to your oil and not informing the lab, your results will be skewed. By introducing additives to your oil you are going to change the elemental additive package, which will vary depending on the vendor of that packaged product, as the base oils have generally the same basic element content. Additives that contain Pet distallate will lower the oils viscosity and the flash point resulting in a false positve for fuel.


The quanitifaction of fuel in oil will be dependant on the type of instrument used for the analysis. There are several types of instruments used to perform fuel detection in used motor oils: Mineral Bath Viscosity, Ft-IR, Flash, Calibrated Fuel detection meter. I just looked and saw that Blackstone uses Flash Point as a determinating factor for fuel contamination.
There are several other factors to understand too. If the component has been sampled on a regular interval then trend analysis of the spectrometric data can be used. Fuel contamination will thin the oil (low Visc) which will lower the elemental results of the spectormetric results.

Also, sometimes Copper will increase due to the fuel washing out the lubricity of the oil making the fine film cushion that normal oil provides. Copper is usually found in the races of bearing and connector pins. Sometime the fuel itself may have dissolved Copper in significant amounts. The only real test for that would be to obtain a fuel sample and have a GC (Gas Chromatograph) Mass Spectrum test run on the fuel, but that is $$ and finding a place to do that ???

Another considaration is if one is submitting samples on a routine interval and using additives intermittantly then one will obtain inconsistant readings over the various samples.

The best approach for getting the best results in your Oil analysis is consistancy in sampling technique, sampling intervals, oil additive introduction. Be sure to advise the Oil Lab with your additive selection and amounts if utilized. Otherwise they are assuming that you do not use additives.

 

[Scot]

Wow, hell of an explaination! I use blackstone and don't use additives. The reason for testing was to see if I could extend intervals. I guess if it stays under 5% I won't worry about it.

Thanks for your input

 

[CHPMustang]

What was driving the test for fuel?

Due to the introduction of ULSD to the US market that it's a fact that the new fuel has been eating injector O-rings which then allows the fuel to pass into the engine oil which can be bad for the oil which then in turn bad for the engine.

I can do $20 oil tests every few months but a new engine,nadda

I don't recommend adding anything to engine oil unless it's a dye pack to trace for leaks.

 

[LA350]

I had a nice big explanation for you but my fat fingers hit the wrong keys and deleted my post. Oh well.

Any fuel contamination inside your engine isn't good. 5% is a lot IMHO and will only get worse over time if it isn't corrected now. Fuel dilution is a killer, it will degrade viscosity, removing your protective cushion that keeps parts from rubbing, and cooling properly. Small tolerances become larger as wear occurs, this wear becomes distributed into your oil stream causing further wear damage. Finally, as in the old exaggerated Castrol TV commercial "thermal breakdown."

I will rewrite it later, too tired now. I can say this is the best way to fully know how your engine is performing internally short of a tear down is to have oil analysis performed on regular intervals. The longer the better because as your truck ages and the hours/miles pile up the more the analysis will benefit by extending the life of that engine.

I have no commercial connection to any Oil Analysis company, so don't get the idea I am a shill for XYZ. One can read up on OA @ Noria Lubrication Oil Analysis and Reliability - Noria Corporation

Again no affiliation, just good info.