Engine Oil Discoloration Guide - What Different Oil Colors Represent

What color is your oil? Don’t know? Relax most drivers don’t. If you do check it and have concerns, here is a guide to what some of the colors may indicate.

Engine Oil Discoloration Guide - What Different Oil Colors Represent

Oil color doesn’t tell us everything, but there are things to watch for.

First, color doesn’t necessarily mean anything. Oil can be very, very dark (black even) and still be effective. However, as a general rule:

  • New, clean oil is amber in color
  • As engine oil gets darker, it can indicate a) high heat, b) contaminants, or c) the presence of additives that cause the oil to darken during normal use.

Therefore, the best way to determine what color your oil should be is to observe how your oil changes color over time. Just pull the dipstick every few days, make a mental note, and at some point you’ll learn to “read” your engine’s oil by color, i.e. you may find that your oil starts to look dark brown after 3,000 miles, and very dark brown after 5,000. If your oil is supposed to be changed every 5,000 miles, than you know that “very dark brown” likely means it’s time.

Of course, if you change oil brands or types, all bets are off. Weather can effect color too (to a lesser degree), so diagnosing oil by color is never going to be an exact science.

Therefore, the best way to evaluate oil color is to look for the obvious issues (outlined below) and then look for other signs of a problem.

Some engine oil colors indicate problems:

  • Milky, foamy, and/or cream-colored oil can be indicative of a head gasket leak, especially if you’re seeing white smoke in your exhaust and your vehicle is losing coolant.
  • Thick AND dark oil usually indicates dirt or contaminants. If you’ve gone off-road and exposed your engine to a lot of dust (for example), your thick and dark oil probably means it’s time for an oil change.
  • Oil with a creamy, frothy texture can also indicate water contamination, so if you are NOT seeing white smoke and low coolant levels (or contaminated coolant) in your vehicle, than water would be the next likely source of contamination.
  • Oil color won’t generally be effected by gasoline contamination, but oil smell will change quite a bit, as the oil will smell much like gasoline. Therefore, you don’t need to look at the oil to check for fuel contaminants, you need to smell it.

Next time you check your engine oil, pay close attention to what color it is. If something doesn’t seem right, have it checked by a certified mechanic right away.

Written by Tim Esterdahl