Engine Oil Color Guidelines
Fresh Engine Oil
Some people judge the quality of an engine oil based on color. Is it better to use a lighter colored oil or one with a darker appearance? The answer is not so straight forward.
Generally speaking, all engine oils come in a shade of amber or golden brown. The differences in shade between types and brands is dependent on the base oil stock used (which accounts for 90-70% of the lubricant) and the types and quantities of additives blended in (which account for 10-30% of the finished product).
While mineral based stocks may be darker due to the higher concentrations of sulfur and aromatics left over from basic crude processing, lubricants made from highly processed and synthetic bases that are purer (thus clearer) can darken upon blending due to the addition of certain additives. So it is very difficult to determine quality with the naked eye alone.
However, regardless of type or brand, the fresh oil should be clear and bright. It should be translucent with no solid particles visible. Changes in appearance of your favorite brand may be due to base oil stock origins or reformulations which more responsible manufacturers should declare to their customers.
Used oil over time
As the vehicle operates, heat plus oxidation and additive depletion occurs and the color of the oil darkens. From amber gold, the oil turns darker and in time loses it’s translucency at 4,000 km.
The amber starts to turn brown and darkens progressively with use. A dark brown oil may still be suitable for use for as long as it hasn’t thickened. A thickened and grainy oil can indicate extreme oxidation and contamination which means you need to change your oil immediately and have a mechanic check your engine cooling system, filters and seals.
On the other hand, used oil can turn into a light, foamy and milky color. This is a very serious problem and normally indicates water or coolant contamination and necessitates immediate change oil and repairs.
- Fresh oil can have different shades of amber for as long as they are also clear and bright.
- Check your oil regularly and use the dipstick to inspect the color of your engine oil over time.
- Expect darkening to occur around 4,000 kms of use.
- It’s all about texture and less about color.
- Darkened oil that still flows freely is ok.
- Thick dark grainy oil or foamy milky oil are not ok and should be changed immediately.