WORKSHOP
In the instances where engines, etc. have been modified, or the equipment has lost its service literature, seek technical advice from an expert.
WHAT DO THE NUMBERS AND SPECS MEAN? The Society of Automotive Engineers( SAE) established a numerical code system for classifying lubricants according to their viscosity characteristics( i. e. how thick or thin they are). SAE viscosity classifications include the following: from low to high viscosity( thin to thick): 0, 5, 10, 15, 20, 25, 30, 40, 50 or 60. The first numbers before the‘/’( 0, 5, 10, 15 and 25) are suffixed with the letter‘ w’, designating their‘ winter’, or cold-start viscosity, at lower temperature. In simple terms, the lower the‘ w’ number is, the better cold start circulation it provides. The higher the number after the‘/’, the thicker the oil is at running temperature. The lubricants industry has its acronyms, for example, JASO is the Japanese Automotive Standards Organisation. They provide a framework of specifications to ensure the correct level of performance is achieved by the lubricant manufacturer. Their specifications address specifically the issue of wet or oil immersed clutches.
ARE ALL SEMI-SYNTHETIC OILS THE SAME? WHAT’ S THE DIFFERENCE? The term semi-synthetic purely relates to the base oils used in the formulation and gives no indication of its performance level in terms of wear protection, cleaning ability, etc. The difference will be the additive systems used to achieve these functions. If you are comparing semi-synthetic products, always look at the specifications listed, as these will tell you if one is better than another.
CAN’ T I JUST USE CAR OIL? Passenger car engine oils are designed for use in … passenger cars. The big difference between car engine oils and motorcycle specific products is their ability to eliminate clutch slip in oil immersed clutch systems. This is especially true with the latest super slippery car oils that are designed to meet car emissions regulations.
CAN YOU MIX DIFFERENT TYPES? The synthetic oils used in engine oils are manmade versions of mineral oil and are compatible with mineral oils. In semi-synthetic formulations, mineral oils and synthetic oils are part of the same formulation. The only downside here is if you mix expensive synthetic oil with mineral oil you will be effectively diluting the advantages that a synthetic oil will provide( good cold start, good high temperature performance and longevity). So, yes, they can be mixed, but the resulting combination will only be as good the lowest performance product. If this falls short of the manufacturer’ s requirements, the engine will not be properly protected.
WHAT ABOUT COPPER / BRONZE IN OLD ENGINES? This issue really relates to gear oils. Modern gear oils contain sulphur compounds as part of their Extreme Pressure( EP) performance properties, which protect the loaded components of the gearbox from wear. With normal steel-based components the sulphur forms an extremely hard sacrificial chemical layer that stops metal to metal contact under load, therefore protecting from wear. In older designs where components may be made from copper alloys( such as phosphor bronze), the sulphur attacks the copper to form a very brittle compound. This will start to break up and the integrity of the gear teeth and the unit will suffer. For classic bikes look for an oil with a higher zinc( ZDDP) content.
I DON’ T RIDE VERY QUICKLY; DO I NEED EXPENSIVE OIL? This goes back to what is recommended in the handbook. Even if a motorcycle is not ridden hard, the oil still has to deal with removing heat, keeping the engine components clean and reducing wear, coping with water condensing in internal air spaces( to stop rusting and corrosion), and ensuring good circulation from
68 KIWI RIDER