Cost cutting with costlier oils
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• In a typical example of a 60-seater bus running 600 or more miles a week, lubrication costs are only 1..78 per cent of the total running costs, whereas maintenance costs are 24.8 per cent of the total. A substantial reduction in maintenance costs might well be achieved by using a higher quality, slightly
more expensive, lubricant.
This advice was given in a paper on lubrication requirements of modern high-speed diesel engines by Mr. D. W. Golothan, Shell International Petroleum NM, which was read by Dr. R; L. Allen of the same company at a meeting of the Institute of Road Transport Engineers in London yesterday. Earlier in his paper Mr. Golothan said that basing the suitability of an oil on specification could be false economy. A series of tests of diesel engines operating on oils "claimed to meet Supplement 1 requirements" and on a number of branded oils had shown, he said, that the latter gave a more satisfactory performance. In service none of the specification oils would have been satisfactory in the case of a modern highly rated engine operating under severe conditions_
Dealing with running-in problems, Mr. Golothan pointed out that the use of modern heavy-duty oils having good anti-wear properties resulted in slow bedding-in of the piston rings. Scuffing could therefore occur when the engine was running under load which increased blow-by. This tended to burn off the lubricating oil on the rings and could ultimately cause seizure of the piston. A special additive oil could be employed for running-in which could also incorporate dispersant and anti-oxidant additives. A number of engine makers were successfully using an oil of this type for running-in their engines.
A low rate of oil flow past the piston rings, normally associated with a low rate of oil consumption, increased the severity of lubrication conditions between the piston rings and cylinder.