While glycol coolant contamination in diesel and natural gas engine oils is a common occurrence, that doesn’t mean it’s something to ignore. There are many ways glycol can leak into engine and other lubricating oils such as defective seals, blown head gaskets, cracked cylinder heads, or corrosion of cylinder liners. Generally, if there’s a failure in one or more of your engine’s gaskets or seals, you’ll get coolant in your oil or vice versa. The side effects of coolant contamination are quite nasty. If a small coolant leak is left undiagnosed, this can lead to severe or catastrophic engine damage. It is estimated that 53% of all catastrophic engine failures are due to coolant leaks. This is why routine used oil testing is an important part of your maintenance program.
Effects of Coolant in Oil
Coolant contamination creates several engine issues which compound significantly the longer the leak is left undetected.
- Coolant causes oils to thicken over time increasing the oil’s viscosity. This can form a thick gel or emulsion, sometimes called “black mayonnaise”. This thickened oil has a reduced flow through the engine and impacts on its ability to properly lubricate engine parts
- Coolant contamination can form water and acids in crankcase oil leading to a loss of soot dispersency. This causes filters to plug and leads to increased contamination from unfiltered particles creating additional abrasion and component damage.
- Oil balls can form when glycol-based coolants mix with oil additives. These can range in size from 5 to 40 microns and are abrasive – oil balls can erode surfaces such as the inside walls of cylinders.
- Glycol breaks down in high temperature engine environments leading to glycolic acid formation. These acids corrode non-ferrous surfaces in the engine and form metal salts.
How to Detect Coolant in Oil
Early detection of a coolant leak is critical. You can start with visual checks of oil and coolant fluid levels and appearance (e.g., looking for black mayonnaise or thickened oil). In-field testing, like the blotter spot test can be used as a quick check if you suspect a coolant leak. For this test, a sheet of blotter paper is placed on a flat surface and a few drops of oil are placed in the middle of the sheet. After an hour, if the oil drop absorbs outward and there are defined “soot rings” with a yellow/brown center, this indicates glycol is present in the oil. If you see a black sticky paste with a well-defined sharp outside ring, this is cause for serious concern. While the blotter spot test is inexpensive and can visually verify the presence of glycol in oil, it is subjective and not quantitative.
A major issue with field testing is that you can’t tell the actual amount of glycol in the oil at any given time. Glycol coolant breaks down rapidly when the oil is in high heat situations or over time. Consider following up on any suspected coolant leaks found in field testing with laboratory testing to confirm the extent of the issue. In-lab testing can include FTIR, ICP Spectroscopy, and Gas Chromatography (GC) and more than one test may be necessary to confirm if a problem is occurring. After the leak has been fixed and system flushed, a follow up oil sample analysis should be done to confirm there’s no further issues.
In summary
Coolant contamination of in-service oils and lubricants is not something to be ignored. Because of the importance of coolant in managing heat transfer in your engines or rotating equipment, routine oil testing of used oils is recommended to detect a possible leak before you may be aware of it.
Contact a Fluid Life representative today and find out how routine and triggered testing can help you monitor for coolant leaks.