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Show IDHiWERS QUICK IS CLASSIFY OIL Selection of Right Kind Smoothes Way oi Car and of Motorist The experience of thousand? of mo-torists mo-torists and innumerable testa marie by the manufacturers of lubricating oils prove thai the best oil that rau hp ob lained is Ihe cheapest in the lone run, for any car. Not onlv because It prevents pre-vents depreciation, saves expensive repair re-pair bills, gives greater gasoline and lire mileage, but also because an oil that Is correct in quality and body wears longer. If the oil la what it should be. it does not burn up under friction heat; it remain? on the surfaces it la supposed sup-posed to protect Oil too heavy or too luht in body works past the piston rings, reaches the combustion cbam j bers and burns there. A carbon de ! posit forms, the engine begin: to knock, and the car is due for an over hauling. But the right oil is not wasted in this way. It remains a buffer to prevent pre-vent friction and to absorb excessive heat generated by the moving parts. The miles of "wear" you get per gal correctly lubricated. SOME QUALITIES OF GOOD OIL. What. then, arc the qualities pi ; good lubricating oil? What must it do while the engine is in operation'1 It must be remembered that the whole theory of lubrication is the prevention, or at least the minimizing, of the effects ef-fects of friction. Tbe moving parts of the machine must be kept apart by a thin film of oil To perform this function properly, the oil must have the correct viscosity, or, less technically, techni-cally, the right body If the oil is too heavy, 't offers resistance to the moving mov-ing parts, especially lo the sliding motion mo-tion of the pistons This resistance not only slows up acceleration, but generates gener-ates a heat that results in the over ; heating of the entire engine. If. on the other hand, the oil is too light in body, U cannot maintain the necessary pro tective film between surfaces. The moving parts come into direct metallic contact and become scored, or even j fused. LITTLE SEDIMENT Lubricating oil of high quality leavi -a minimum of sediment or carbon residue after being consumed. This carbonization depends upon tin viscosity viscos-ity volatility, susceptibility of the oil towoxidatlon and the amount of leakage leak-age past the piston rings. Lubricating oil of high quality ha-a ha-a nigh "flash-poin; " In uon U i bnical language the flash-point is Hip lowest temperature at. which the oil vapors it; nlte without setting fire to the o:l i-self. i-self. If the flash point is too low. It means that the oil will evaporate from the moving surfaces it is supposed to protect, allowing friction. 'A. good lubricating oil must also show a high test This la th- lowesl temperature at which the oil Itself ik nites and burns. Thr blcher the temperature tem-perature in this test, the more you are assured of lubricating efficiency There are other qualities which a good lubricating oil should possess, but ihey are more or less technical and concern the refiner and cbemlst more than the consumer. |