Virginia Auto Service

What is Motor Oil Sludge – And How Can You Prevent It?

Motor oil is often considered the lifeblood of your vehicle. Having regular oil changes is probably one of the most important maintenance tasks performed on your vehicle.

Motor Oil Sludge

Motor oil lubricates the moving parts of your engine, reducing friction and keeping the engine cool. When the oil is new and unused it is a transparent and easily flowing liquid that combines a base stock with various additives. The additives hold soot and other particles while maintaining the consistency of the oil. With use, the oil builds up contaminants such as fuel, dirt, water, coolant, etc. It also oxidizes due to the intense heat of the engine. The combination of contamination and oxidization turns the oil into “sludge,” a gel-like fluid that can seriously damage your engine.

A basic understanding of how motor oil works:

Motor oil is either synthetic or conventional and absorbs and protects the engine from contaminants. However, after a period of time, the oil will reach its absorption capacity. When this happens, instead of carrying contaminants away, it will deposit them on the engine surfaces and any other parts in which it circulates. It will stop lubricating the engine and reducing friction and, instead, cause heat to build up in the engine. Clean motor oil acts as a sort of coolant for the engine, however, when it becomes oxidized sludge, it acts as the opposite. When the oil becomes overly oxidized and contaminated, turning into this sludge, you will notice that the oil pressure falls and that you get lower gas mileage.

Motor oil sludge development:

  • Motor oil sludge first accumulates on the top of the engine, in the oil pan, and the valve cover section.
  • Then it blocks the oil screen siphon and prevents oil from circulating in the engine.

When motor oil sludge develops you risk serious engine damage as well as damaging the timing belt, gaskets, radiator, and cooling system. If not taken care of, motor oil sludge could cause the engine to stall completely.

How motor oil turns into motor oil sludge:

  • When it is exposed to oxygen under high-temperature conditions, the motor oil oxidizes. The oxidation occurs more quickly when the motor oil is heated for longer time periods.
  • When the oil oxidizes, the motor oil molecules break down and combine with the dirt, metallic particles, fuel, gases, and other contaminants forming the thick, sticky sludge.
  • Heavy stop-and-go traffic can contribute the buildup of motor oil sludge, as well as frequent short trips.

How to avoid motor oil sludge build up:

  • Have regular oil changes performed per the intervals laid out in your vehicle specific owner’s manual.
  • When you start your car, check the dashboard for the Check Engine light and/or the Oil Change notification light. Either light may indicate the need to replace your motor oil.
  • Avoid driving in stop-and-go driving as much as you can. Also, avoid taking too many short distance trips. Walk, bike, or consider public transportation when possible.
  • If the gauge on your dashboard shows that your vehicle is heating up, make sure your mechanic checks for motor oil sludge.
  • If you see the oil pressure is low, avoid adding engine oil and instead have your vehicle inspected for motor oil sludge. If the oil pressure light is on, you should have it inspected and/or replaced completely as soon as possible.

The most important thing you can do for your vehicle is to make sure that you are always following the maintenance guidelines laid out in your owner’s manual. This is especially important when it comes to the motor oil, or you risk serious and expensive engine damage.

If your Check Engine light or Oil Change notification is on, schedule an appointment with Virginia Auto Service. We will check the engine for signs of motor oil sludge build up and let you know if your motor oil needs replacing. We may also check for other reasons why the light has come on. We will relate any findings to you and thoroughly go over your repair options and costs.