Engine sludge - The silent killer

Engine oil is the life blood of any engine. It takes care of the main adversary of the internal combustion engine- friction. And in the same time cleans it and gets rid of all that heat inside it. It's responsible for everything from the smoothness of your engine to how long your timing chain lasts. Engines are so dependent on the stuff that, believe it or not, the ware which takes place in a single stroke of the piston without engine oil is equivalent to that of 50 miles with engine oil! This fact alone gives us a clue that this is not a subject to be taken lightly.

Lately, a new phenomenon is enveloping modern petrol engines that causes their untimely death and a main factor that leads to this is the same life giving motor oil, especially synthetic motor oil. It's called sludge formation and it's on the rise, according to reports and customer complaints filed against automakers around the world, especially in the US. The phenomena effects motors that are made after 1996 and, through much investigation and analysis, engineers have been able to trace the root cause on the high temperature levels caused by leaner fuel mixtures that are present in modern engines.

The phenomena is most prevalent locally in cars that (according to manufacturer's recommendations) use 95 octane petrol and use fully synthetic engine oil.

The formation of sludge can be attributed to a complex interaction between soot, engine heat, additives in fuel, additives in engine oil, water, acids and dirt. If left unchecked (if engine oil is not changed regularly), the sludge will cause friction among moving metal parts, and finally result in the engine seizing. Since sludge begins to appear in the oil pan and the valve covers, an easy way to identify if this problem is occurring in your engine is to remove the oil filler cap and check for any traces of sludge forming under it. At the same time it should also be stressed that this is a do-it-yourself test and doesn't carry any conclusive evidence that sludge formation is taking place as normal engines have a small amount of sludge and condensation present at this 'high point' of the crank case.

A more sure footed approach to the matter is to check the engine oil level regularly and use high quality oil and a filter when your next oil change is due. The fact that engines operating on synthetic oils are more prone to the problem can be traced down to the long oil change intervals taking place in them, sometimes even over 15,000 km. Be sure to change synthetic oil every 8-10,000 km and normal mineral oil every 3-4000 km. Regardless of the mileage, it is also wise to change the engine oil (and filter) every six months. This is most relevant to local conditions where most cars will not cover mileages mentioned above within six months.

You should also keep an eye on the EGR system and the PCV valve to see if their working properly. Manufacturers normally recommend the PCV valve to be changed every 50,000 km and recommend a coolant change at the same time. So, if you can do both, all the better. Another contributor is a neglected air filter that lets fine particles escape in to the intake, as in our local conditions the air cleaner should be cleaned once every 1000 km and replaced once in 10,000 km. Even the petrol filter should be checked regularly for blockages and leaks and should be replaced if necessary. Stick with our advice because we know what engines want! Stick to these recommendations as a rule of thumb and always keep a record and/or history of oil and filter changes and you motor will be as good as new for some time to come.