Modern engines and lubricants are far superior to those of even ten years ago. As a result, most vehicle manufacturers now recommend engine oil changes every 5,000 or 7,500 miles under normal operating conditions. However, the auto service industry has long encouraged more frequent oil changes based on the belief that most drivers operate their vehicles under “severe service” conditions. But do they really?

Today, mileage-based oil change intervals are becoming a thing of the past. A growing number of new vehicles are equipped with maintenance reminder systems that determine the need for oil changes based on the owner’s actual driving habits. In practice, most drivers find that these systems call for an oil change at around 7,500 miles and, on vehicles factory filled with synthetic oil, the change interval may be as high as 15,000 miles!

Another outdated belief is that oil color is a valid indicator of the need for a change. While new oil has a light gold to brown tint, the fact that oil in service turns dark brown (or black in diesel engines) does not mean it is “dirty” and needs replacement. It only indicates the detergents in the oil are doing their job of keeping tiny particulates in suspension, while any contaminants large enough to cause engine wear are trapped by the oil filter. In fact, because of their superior detergent packages, synthetic oils often turn darker faster than conventional oils.

Checking Engine Oil
It is easiest to check the oil level when your engine is cold. There is no possibility of burns, and cool oil stays on the dipstick better, making it easier to measure the level. If you have been driving, wait a few minutes before checking the level to allow oil to drain back into the oil pan.

  • Park the vehicle on level ground with the engine off.
  • Open the hood, then find and remove the engine oil dipstick.
  • Wipe the end of the dipstick clean with a rag, and note the level markings. Some dipsticks have one mark for FULL and another for ADD. Other dipsticks may simply have small holes indicating the maximum and minimum oil levels, still others may have a cross- hatch area indicating the acceptable range.
  • Insert the dipstick fully back into its tube, then remove it immediately and read the level.
  • If the oil level is at or below the ADD mark, then add enough oil to bring the level up to the FULL mark. Do not overfill. Typically, the distance between the ADD and FULL marks is equal to one quart of oil.
  • If the oil on the dipstick appears milky or thick, or is very thin with a strong fuel odor, there may be a mechanical problem. Have the engine checked by a qualified technician.

Sierra Car Care recommends that motorists carefully review the oil change interval recommendations in their vehicle owner’s manual, including the definition of severe service use, and then change their car’s engine oil only as often as really necessary. While over maintaining your vehicle won’t hurt the engine, it costs more money and consumes additional natural resources.