A sheet of common blotter paper is placed on a flat surface and a dipstick is used to place a few drops of oil in the middle of the sheet and left for an hour. If the oil drop absorbs outward and there are defined “soot rings” with a yellow/brown center, that is qualitative evidence that glycol is present in the oil.

Go out and pop the hood, pull the dipstick and check the color of your oil. It can tell you if the precious lubricant is contaminated, if there is something such as water getting into the system, and how old the oil is. The four most common colors for used engine oil are amber, brown, black, or cream.

The effects of coolant and antifreeze contamination are many. One is simply a rise in the oil's viscosity or a thickening of the oil. This often produces what's called black mayonnaise, which is a thick gel or emulsion when mixed with the oil.

Glycol, the principle ingredient in antifreeze, is typically mixed with water 50/50 to form a liquid “coolant” to transfer heat, raise boiling point temperature (above 225°F or 107°C) and lower the freezing temperature (below -32°F or -35°C).