The easiest way to prevent engine sludge from building up and causing damage is to ensure that you change your oil regularly. Clean oil simply performs better throughout the vehicle’s oil change interval, but once it is worn out and contaminated, it should be replaced to avoid sludge from taking hold inside the engine. There is also an indication that the use of synthetic oil can reduce the risk of engine sludge buildup, as it is free from the impurities present in conventional motor oils. For maximum protection, it may be best to switch to a full synthetic oil, like SYNTEC Powered by O’Reilly®, but maintaining your oil change schedule is still an important factor.
Engine sludge is a common phenomenon in automotive engines, but its causes may be less well-known. Oil sludge occurs when oil breaks down, and sludge buildup can prevent oil from properly lubricating your engine, resulting in permanent damage if not addressed promptly. If you suspect the presence of engine sludge, or if you’d just like to learn more, read on to discover how engine sludge forms and what you can do to prevent further buildup and remove sludge to limit the risk of damage.
What Causes Engine Sludge?
Engine sludge can be caused by a few different factors, but most of them relate to engine temperature and proper oil vapor ventilation. It’s possible that frequent stop-and-go driving and shorter commutes, which typically contribute to lower engine temperatures, can cause sludge to form. Extremely high engine temperatures, typically those over 212° Fahrenheit, can also cause excessive oil evaporation, and when the vapor escapes, it can leave sludge behind.
The PCV (Positive Crankcase Ventilation) system is designed to recirculate oil vapors to the intake to be burned, and also allows the crankcase to relieve pressure to prevent vapor buildup from harming the engine or hindering performance. If a PCV valve is clogged, no longer connected, or leaking, it can also be a contributor to the development of sludge in the engine. PCV valves are often very easy to remove and test, and you can learn more about how to diagnose and replace a bad PCV valve with our helpful video.
The longer contaminated oil remains in your engine, the higher the risk of sludge formation. This means that frequent and regular oil changes can help stave off sludge buildup, as well as ensure that your engine always has fresh, clean oil to maintain lubrication. Checking engine oil regularly and topping off oil levels when needed can also help you stay ahead of the development of engine sludge and provide confidence in your engine’s continued performance.
What Does Oil Sludge in an Engine Do?
Oil sludge is bad for your engine in a number of ways. The most notable problem with sludge buildup inside the engine is that it reduces the engine’s ability to lubricate its moving parts. This can quickly lead to wear and damage that may render your engine inoperable. In addition, oil sludge can clog oil passageways, making it impossible for oil to even reach the parts of the engine where it is needed. This can cause low oil pressure or an oil pressure warning light, which are both clear indicators that your engine has an oil delivery problem and needs immediate attention before you continue driving the vehicle. Sensors attached to the engine can also be fouled by sludge buildup, which can cause the Check Engine light to activate, and can result in performance problems due to inaccurate communication with the engine control unit (ECU).
In vehicles equipped with variable valve timing (VVT), it is even more important to prevent the buildup of sludge by using the manufacturer’s recommended oil type and adhering to recommended oil change intervals. VVT systems use pressurized oil to power the VVT actuators, and if this oil pressure can’t reach the actuator, the engine timing may suffer and cause severe performance issues. This may lead to even more costly repairs than typical sludge buildup, and a qualified service technician may be required to help save your engine and replace the necessary components of the VVT system.
How to Prevent Engine Sludge
Though it may not be possible, avoiding stop-and-go traffic can help slow the buildup of engine sludge. If you have a vehicle you typically only drive for short distances, it may be a good idea to make sure the vehicle runs for at least 15-20 minutes once it has been started. This gives the engine time to warm up to operating temperature, and ensures that it cools down slowly once the engine is turned off. This not only helps prevent engine sludge from accumulating, but also prevents moisture from damaging the exhaust system, allows coolant to circulate to prevent scale buildup, and more.
DIY Engine Sludge Removal
If your engine is already experiencing sludge buildup or if you’ve noticed symptoms that may point to the presence of sludge in the engine, there are a few things you can do yourself before taking the vehicle in for professional service. The first step is to perform an oil change using an oil with specific additives that are designed to fight sludge buildup. These additives, specifically anti-oxidants, detergents, and dispersants, are designed to prevent or limit oil oxidation, suspend contaminants to prevent them from aggregating, and neutralize acids that are generated during the process of sludge formation.
Sludge removal products also exist in the aftermarket that are designed to clean the engine internally and remove sludge during your next oil change. Engine flushes and oil treatments can help break down the sludge and flush it from the system before more oil is added. These are often not a single-step application, and depending on the severity of the sludge buildup, you may need to use these additives and change your oil more frequently until you see that sludge is no longer present in the oil that is drained.
In more extreme circumstances, especially cases where sludge buildup causes oil starvation, it may not be a good idea to run your vehicle for any period of time. Since engine flushes require the engine to run for several minutes, you may risk damaging the engine attempting to use these products. In that case, it may be necessary to remove the oil pan and clean engine sludge out by hand. Oil pans are often easy to remove from the vehicle if they are unobstructed, and once it is removed, the sludge can be removed manually and the oil pan and oil pump pickup cleaned to ensure oil can flow freely again. Always be certain to replace the oil pan gasket before reinstalling the pan, and fill the vehicle with fresh oil after performing this service. Though this may not clear all the sludge from the engine, it can help you be certain that the engine has at least the minimum necessary oil pressure before using a chemical flush and treating the rest of the engine.
More severe sludge removal can be a daunting task, and depending on the situation, may require the engine to be at least partially disassembled. If that is the case, it may be best to contact a trusted repair shop to make these repairs and get your engine back in operation. If you don’t have a regular mechanic, O’Reilly can recommend service centers in your area using our Find a Repair Shop tool. Engine sludge removal cost can vary wildly depending on the amount of sludge or the symptoms that the engine is experiencing, but generally this will require significant labor and may be prohibitively expensive.
The old adage 'an ounce of prevention is worth a pound of cure' is especially true when it comes to engine sludge. Keeping up with a regular maintenance schedule can help prevent excessive oil change intervals that can lead to sludge buildup and is typically the best approach to avoid having to deal with this issue. If you perform an engine flush, it’s a great opportunity to switch to a full synthetic oil and keep up with recommended oil changes to prevent engine sludge buildup from happening again. Though oil sludge removal can be costly, the basic steps to prevent oil sludge are relatively inexpensive and can help keep your car on the road for as long as possible.