Engine Sludge and How to Prevent It

Sludge. Just the word sounds potentially bad.  And if you find sludge inside your engine it is definitely bad.  What is it?  Think of it as a black goo that plugs lubrication holes, fouls sensors, and prevents your engine from running well.  How does your engine oil turn from a cooling and lubricating fluid to sludge that may destroy your engine?  It’s quite a process to get there, but preventing it is easy.  Let’s find out how it all happens.

Engine Sludge

How Does Engine Sludge Form?

Engine sludge is a by-product of a series of chemical reactions that can take place inside your engine. Engine oil degrades as it is exposed to oxygen and elevated temperatures. The higher the temperature, the faster the rate of degradation. For every 18°F (10°C) increase in temperature, the rate of oxidation and degradation will double.

The chemical process of degradation, the lubricant breaking down, forms highly reactive compounds.  These compounds continue to break down the engine oil.  The products of the breakdown form organic acids.  They also form high-molecular-weight polymeric by-products.  The acids and polymeric by-products continue to chemically react.  They eventually form the sludge that will plug your engine and prevent proper lubrication and cooling.

What Does Engine Sludge Buildup Do?

Your engine oil is a thin lubricant that travels through passages inside the engine and keeps everything lubricated. The oil works in conjunction with the engine coolant to keep the engine cool, and the ability to travel is a necessary requirement to keep your engine healthy. A thicker oil, especially a degraded oil that is turning into sludge, won’t be easily pumped through the oil passages.  The engine oil pump can’t draw oil through the pick-up screen and pump through the oil passages.  The result of the blockages and lack of oil causes oil starvation.  This further causes potential overheating of the bearings and moving parts.

Many of the newer engine designs, particularly those with Variable Valve Timing (VVT) rely on oil pressure to adjust valve timing for maximum power and efficiency. Engine sludge can plug those pressure sensors that adjust the timing of your internal combustion engine. Over time that can reduce efficiency of the engine, increase wear of the engine, and lead to higher maintenance.

How Can I Prevent Engine Oil Sludge?

This may seem like a trick question since oil degradation is the basis of engine sludge. The simple answer for prevention is to run a quality engine oil and change it often to prevent the sludge from forming.  Changing the oil and filter frequently, whether that is at the age old recommendation of 3,000 miles or 3 months, is a good starting point for basic petroleum engine oil. You can extend that time and mileage by using a better engine oil and filter. Synthetic oils, such as AMSOIL Synthetic Engine Oil, have a quality base that will reduce oil degradation even at higher temperatures. In addition to high quality base oils, they also include antioxidant additives and detergents that prevent thermal breakdown plus will keep your engine cleaner internally.

Some of the additives commonly used in engine oil include zinc dithiophosphate. This additive prevents oxidation, but also adds an anti-wear property to the engine oil to help with durability of the engine bearings and moving parts. Other additives like dispersants are part of a quality engine oil formula which promote the suspension on engine contaminants within the oil to keep them from building up inside the engine and potentially clogging oil passages. Detergents include in the high-quality formulations are alkaline (basic) in nature, which offset acidic properties of engine sludge. They will help to prevent the acidic breakdown of engine oil.

What is the Best Synthetic Oil to Use?

Ok, you caught us on this one. We’re a little biased on this answer as Buy Great Oil offers AMSOIL products in our online store. We use AMSOIL exclusively in our fleet of vehicles and equipment because their oils include 50% more detergents than some competitors. That cleaning helps to keep engine oil passages clean and prevent blockages and advanced engine wear. We can run our engines harder, longer, and don’t have to worry about engine damage due to thermal breakdown. AMSOIL oils offer 90% better protection against sludge formation, and that is piece of mind we enjoy.

It’s pretty easy to overlook maintenance on our vehicles as we’re all extremely busy. Given that many new vehicles are only increasing in purchase price, keeping your older vehicle on the road with excellent preventative maintenance may just be the best option. Today’s synthetic engine oils, such as AMSOIL Signature Series 5W-30, can be used well beyond 3,000 miles between oil changes without risking lubrication performance. Partnering those with superior AMSOIL EA Filters will keep your oil performing at its best also. If you need help with determining a complete maintenance plan for your vehicle, your local AMSOIL dealer at Buy Great Oil is here to help with a complete package of products and hints to make the job easier.

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