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How can I test whether oil is leaking into cylinder combustion chambers and getting burnt in case of oil level loss? As opposed to, for example, leaking through the oil pan or the timing chain cover.

  • 2
    Fastest way is using an exhaust gas analyzer, if oil is burning in the combustion chamber it will cause really high hydrocarbons in the exhaust. – Moab May 1 '16 at 18:44
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Pull the spark plugs and inspect them.

Oil-fouled spark plugs will look wet and black.

Spark Plug Chart

  • That is a really old poster, today's modern lean burning engines will not show those types of deposits. – Moab May 1 '16 at 18:29
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    @Moab While it is true that some of these conditions have become quite rare in modern computer controlled fuel management systems. They are all still valid. Oil ash on the plugs is still a good clue to oil burn and we see it often enough. – Fred Wilson May 1 '16 at 19:17
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You can test your rings and head gasket with a leak down tester

Checking your spark plugs as shown in @Zaid's post is the first order of business. You will see it on the plugs.

Now, if you do see an oil fouled plug, you will need to identify the source of the oil.

Possible Sources of Oil

  • Intake valve guide seal

  • Rings

  • Head gasket

  • PCV valve

Any of the above can be a source of oil into your engine where it can be burned.

To test the integrity of the combustion chamber you can use a leak down tester. A leak down tester will pressurize your combustion chambers and allow you to listen at your intake and exhaust valves for leaks as well as your crankcase ventilation for head gasket and ring leaks.

Here is post regarding how to use a leak down tester.

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