Can Oil Analysis Show If Antifreeze Is In Engine Oil?

A reader asks: My car’s coolant level keeps dropping. I’m concerned that it is getting into the engine oil. Can oil analysis show if antifreeze is getting into the engine oil?

Our answer: Yes, oil analysis can detect the presence of antifreeze in engine oil. This would show up as elevated sodium and potassium. The report would “red flag” these elements. There would also be a note in the comment section warning that antifreeze has been detected.

How Can You Tell If Antifreeze/Coolant is Getting Into The Engine Oil?

If the coolant level is dropping, look for milky brown residue on the dipstick. This can be a sign that antifreeze is present in the engine oil. Also look for signs of engine oil contamination in the coolant reservoir (also known as overflow tank).

It is important to note that moisture (and not antifreeze) can sometimes be observed on the dipstick and on the under-side of the oil fill cap in winter. Moisture can be generated by frequent short trips when the engine is not getting up to operating temperatures. This condition is generally not harmful.

The surest method of determining if there is antifreeze in the engine oil is to perform oil analysis. Oil analysis is relatively inexpensive and scientifically accurate. We can offer this service from labs in both Canada and the US.

For more information, call us at 1-800-748-5781 or contact us using the form on this page. Be sure to put “oil analysis” in the comment section.

How Harmful Is Antifreeze Contamination Of Engine Oil?

Antifreeze contamination of engine oil may cause extensive damage and can ultimately lead to engine failure. Coolant getting into the engine oil can be damaging on a couple of fronts.
First, antifreeze can cause corrosion which can ruin engine internals. Second, antifreeze dilution compromises a motor oil’s viscosity and also alters its protective ingredients.

How Does Antifreeze/Coolant Get Into The Engine Oil?

The most common cause of antifreeze/coolant getting into engine oil is head gasket failure. A head gasket failure can be caused by extreme engine overheating. Some engine designs are prone to head gasket failures. Another possible reason for antifreeze contamination of the engine oil is a cracked cylinder head or engine block.