Above: Cooling gallery under the piston crown - vulnerable to deposit build-up.
Above: Insolubles Test Cell
Below: Cap half of big end bearing. Scaring and pitting caused by embedding of particles from contaminated oil.
Info Centre >> Fuel and Lube Oil Technical Manual >> 7. Lube Oil - Test Results >> 7.2 Diesel Engine Oil >> 7.2.4 Insolubles
Insolubles in Diesel Engine Oil
Contamination comes mainly from combustion products, fuel ash, carbon and partially oxidised fuel plus a small contribution of oil oxidation products and spent lubricant additive. The major contributor is soot from combustion and this is measured in the insolubles test.
Insolubles constituents:
The dispersancy and detergency of the lubricating oil will be affected and this will quicken the tendency for deposit buildup around the upper piston, piston ring pack and under the piston crown.
As levels of combustion contaminants in the crankcase rise due to poorer fuel and small sump volumes, combustion gases and vapour can condense in cooler, low oil flow areas. A phenomenon known as ‘black paint’ is believed to be caused by this condensation, affecting oil dispersancy and allowing carbon insolubles to plate out. Another proposed source is precipitation of asphaltenes from fuel leakage due to contact with highly paraffinic lube oil stocks.
Insolubles levels in the crankcase of a gas engine are usually very low due to clean combustion of gaseous fuels.
Insolubles in aeroderived gas turbines are sometimes referred to as ‘Black Oil’.
High insolubles levels will cause: