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PICK YOUR OIL MAN'S BRAINS...

9th September 1977
Page 53
Page 53, 9th September 1977 — PICK YOUR OIL MAN'S BRAINS...
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Which of the following most accurately describes the problem?

ALL the lubrication requirements of the various engine manufacturers, however long and complicated the individual classification, can be streamlined down to two basic specifications.

Going back a few years, the original specification standards were laid down by the American armed forces and subsequently adopted by just about everyone else. The current derivatives of those early standards are still known as "military spec".

The two current -US military specifications" are MIL-L-46152 and MIL-L2104C. The former relates to petrol engines in the main including those operating under arduous conditions and certain naturally aspirated diesel engines. Oils to this

specification are intended primarily for mixed fleet applications.

Specification MIL-L21 04C covers the full requirements for the diesel engine including the highly turbocharged variety. An additional claim is that oils meeting this standard can also be used for petrol engines giving protection against low temperature deposits.

They are a considerable improvement over oils meeting the old Caterpillar Series III specification.

It is essential for the commercial vehicle operator to have a good relationship with his local oil man. Each vehicle has a handbook and in that book is often a bewildering array of oil specifications for that particular vehicle. These are usually represented by a string of numbers which are meaningless to the average operator. Somewhere along the line there has to be a rationalisation.

In conjunction with his local oil company representative, the operator has to choose between getting down to, say, two grades of oil or even one. He will be better off if he can use only one oil throughout his fleet. Most good ideas have a penalty: in this case it is that the one grade which meets all requirements is often more expensive. Providing a narrower choice has another advantage—if you've got two grades of oil, it is always possible to choose the wrong one!

In general terms, a premier multigrade oil can be used for every application.

For example, Deusol RX Super 15W/40 could be selected for simplicity in most types of vehicles whether for long haul or stop/start distribution work, turbocharged or naturally aspirated.

There is always one engine which can't use the same oil as everyone else and that is the Detroit Diesel two-stroke. This is because General Motors set a maximum figure of one per cent for the ash content of the lubricant which effectively precludes most multigrade MIL-C oils. In effect this means that one extra oil is necessary if there is a Detroit Diesel power unit anywhere in the fleet.

For comparative purposes, Cummins put the maximum ash content at 1.8 per cent, which lets in most MIL-C oils and lessens the problem of oil selection.

The local oil supplier, therefore, should have a wide knowledge of the performance of the various oils based on the experience of a large number of fleets. He may often be able to reduce the individual's requirements to one brand name. Most oil manufacturers produce a wide range of lubricants, including the basic monogrades and the multigrades.

The arrival of the multigrade helped to reduce the choice by covering a range of viscosity with the one oil. However, some manufacturers are still reluctant to accept the concept, more because of conservatism than any basic performance reason. Because of this Castrol still markets Deusol RX Super in straight monogrades as well as a 15W/40 multigrade.

The theory of one multigrade oil for all engines has been well proven in practice in both viscosity and performance levels as well as exceeding most military and manufacturers standards.

If there are no turbocharged engines in the fleet, then a lower specification oil will be perfectly adequate. Because of this Castrol still markets separate oils for both naturally aspirated and turbocharged power units. As far as monogrades are concerned, Castrol sells most in the SAE 20 and 30 categories with comparatively little of the SAE 10 and 40.

Oil costs feature as a very small part of the overall fleet transport costs so even if a multi-purpose oil is more expensive initially, the advantages it brings should more than compensate for the extra initial cost.

So the choice still comes down to the individual operator and his own particular operating requirements. He can choose a straight monograde, a multigrade or an all-purpose oil which will cover turbocharged and naturally aspirated diesels and petrol engines. He has only to contact his local oil representative to get the best oil for his fleet.

• Graham Montgomerie

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