Detergent oil (En)

What swims there in our crankcase?

For those amongst us, wobbling around on a Royal Enfield Diesel…There is a typical contamination. During the combustion of the diesel, a lot of soot is produced. These soot-particles come into the oil and might form sediment on the crankcase.




Sludge is more like a pasty, sticky substance which has the tendency accumulating in small corners, along oil bores and on the bottom of the crankcase.



Sludge is generated most at low engine temperatures. It is formed out of mixing water vapor or condensate with oil particles and decomposition materials from the oil and combustion. At the beginning, sludge is so small it is not strained by the oil filter. This start sludge also does not provoke extra wear or damage to the engine, as long it stays as a dispersion in the oil.

The problem starts when the sludge particles stick together and form bigger lumps, obstructing a good flow rate of the oil.

Sludge formation is promoted by a rich (air/gasoline) mixture, often the case at starting conditions. A dirty air filter or some misfiring increases the amount of sludge in the engine oil.


oil varnishDifferent components from the oil tend to react, in the presence of oxygen from the air, and form complex compounds. Affected by the heat of the engine, these compounds are baking into the hotter parts. Hydraulic lifters, piston rings and bearings are often subject to varnishing. The accumulated varnish layers prohibit by time, a good functioning of the engine.

Most of the commercial oils content detergent additives and will take care of sludge and varnish. But, I like to use an extra bottle of detergent oil when exchanging the oil on my bike. Just pouring in the detergent oil, driving around for 10 minutes and drain it. It gives me the certainty that the inside of the engine is clean.

Recommended products:
CRC Motor Flush ; LiquiMoly Motorbike Engine Flush


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