Understanding Oil Contaminants

Let’s start with an update on the new diesel motor oil categories. After five years of testing between the oil companies, the American Petroleum Institute (API) and the engine manufacturers the API has approved the oil for sale. The proposed category PC-11 has been divided into two new categories CK-4 that will replace the current CJ-4 oil designed for current engines and FA-4 that is designed for engines built in 2017. API CK-4 and FA-4 will hit the market December 1, 2016 and can be identified by the API Donut symbol on the back of the oil container. Both oils are formulated to improve fuel economy and provide additional protection from oxidation, engine wear, the effects of low and high temperatures and carbon deposits. These improvements should help extend oil drains by maintaining satisfactory oil quality etc.

Here are a few questions that were submitted:

I have an increase in viscosity and oxidation coupled with a sizeable decrease in total base number (TBN). What could be causing this combination? The answer is HEAT, the oil is overheating that causes an increase in chemical reaction that adds oxides to oil and causes the base additives calcium, magnesium, phosphorous to lose potency. The added heat will cook the oil causing it to thicken and the viscosity will increase. The cause of the excess heat can be as simple as running with low oil levels, a defective oil cooler, or restricted flow in oil galleys or turbo charger. The low level of oil does not allow the oil to cool in oil pan before starting a new oil cycle through engine. A blocked oil cooler will not allow the oil to dissipate heat and restrictive flow keeps oil in engine longer increasing heat levels.

My oil sample has high potassium but very little sodium that would indicate an antifreeze contamination of my oil. Where could it be coming from? Potassium is a major ingredient in preservative compounds that are used to protect engine parts from corroding while on the shelf. Usually when I see this I ask if any parts that come in contact with the oil have been replaced recently i.e. oil coolers, turbo chargers, oil pans, charge air coolers (potassium with aluminum) etc. If no parts have been replaced, then the contamination could be environmental or from an oil additive.

My oil sample results were showing high fuel dilution that caused my viscosity to drop a grade. I added a viscosity stabilizer to bring the viscosity up to correct grade. Am I putting my engine at risk for failure? While the viscosity stabilizer will bring the oil back up to the proper grade, you are just masking a fuel dilution issue that eventually will cause serious damage to the engine. Bear in mind that most oil analysis labs will not perform a Gas Chromatography test if the viscosity is within the parameters for your grade of oil. They will report a < 1% level based on the viscosity level without actually testing for fuel dilution. Therefore you would never know you have fuel dilution that is eroding the wear metal additive package in your oil that protects metal-to-metal wear. Gas Chromatography will report the actual level of fuel dilution in spite of the viscosity levels. I have seen fuel dilution at over 10% with a viscosity of 14.5 on a SAE15W40 oil (12.3-16.2) that would not have detected a serious fuel contamination issue. I find it is always best to fix a problem rather than mask it to avoid engine failures.

If you have any questions on oil sampling results or oil in general please send them to me at: [email protected] and I will provide answers in this column.