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Decoding What Your Engine Oil Color Says About Your Engine Health

Engine oil color can vary and alert you to problems with your motor.

You can think of your engine oil color as a sort of unofficial communications channel between what’s going on inside your motor and the outside world. Although not quite as verbose as spark plugs when it comes to tipping you off about the details of internal combustion, oil and the way it looks can help you get an early start on diagnosing a number of potential problems with your engine.

Check out these oil color variations, and what they might be telling you about your motor’s health.

Dark, Thick Engine Oil Color

The oil you pour into your engine is a light amber-like color right out of the bottle, but after spending a few hundred miles inside your motor it starts to darken. This is completely normal, because modern oil contains detergent additives designed to help clear out gunk from inside the motor and then hold it in suspension so it can’t cause any harm. The thing is, the longer you drive between oil changes, the darker your oil will get. Once it starts to noticeably thicken, it signifies that it’s become saturated with particles of dirt and grime and needs to be swapped out soon.

It’s worth noting how dark your oil gets each time you check the dipstick, especially if you drive on dusty roads or under extreme conditions of temperature or performance (such as towing or racing). This helps you discern whether you need to change lubricant before the factory schedule asks you to.

Muddy Brown, Creamy or Milky Engine Oil Color

Milky OilWhile dark oil is no cause for immediate alarm, if it happens to turn creamy or brownish, you’re probably looking at a serious problem. This engine oil color indicates that antifreeze from the cooling system has gotten mixed in with your motor’s lubricant — almost always due to a failure of the vehicle’s head gasket. If you notice this unusual oil color, first check your radiator or overflow reservoir to see if it’s low. Next, check the tailpipe for white smoke coming out of the exhaust system.

If one or both of these additional symptoms are present, it’s time to schedule an appointment with your mechanic, and drive as little as possible in the meantime. If the oil looks creamy but you don’t notice any smoke or disappearing coolant, water may have entered your engine elsewhere, which means you’ll still want to visit the garage for an oil change and a more thorough diagnosis.

Check out all the chemical & lubricant products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on what your engine oil color says about your engine health, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.

Benjamin Hunting View All

Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time.  I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.

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