High Road and By-Road

Waikato Times, Volume 107, Issue 17994, 12 April 1930, Page 24 (Supplement)

High Road and By-Road

OIL FOR CARS. ONLY A THIMBLEFUL WORKS. Out of the gallon or two of lubricating oil that is put into the crankcase of a motor not much more than a thimbleful is really working at one time, says Mr M. Wall, service manager of General Motors New Zealand, Ltd. This thimbleful consists of the thin film that lines the cylinder walls, keeping the pistons sailing up and down, and prevents the journals from wearing against the bearings. Yet this tiny amount must be viscous enough to remain intact during the lubricating

process, but must not be so heavy or thick as to cause a drag upon the moving parts. It takes a highly efficient oil to be able to withstand the high explosion temperature in the cylinders of motors. This temperature rises to about 2800 degrees Fahrenheit enough to melt platinum—and only a good viscous oil can keep from breaking its film and cause scoring of cylinders and leakage of gases under this continuous battery. professor A. M. Low, the great English physicist, says that oil must not be very stiff when cold, In order to enable the moving parts of the engine to operate without hindrance; neither should it be watery when hot. It must not readily combine with the benzine that happens to leak past the piston rings, nor must it form a watery sludge with’any of the condensed steam

A COLUMN FOR MOTORISTS.

from the burnt gases that leak into the crankcase. “Even the best polished cylinders are composed of a number of small lumps and dents when viewed through the microscope,” he says, “ and these must be filled up and ‘ oxcused ’ by the oil. That points to the necessity of having good oil at all times in the crankcase. Every manufacturer knows exactly what kind and grade of oil is best for his motor. His advice, included in the instruction hook that accompanies every General Motors car, should he followed religiously if he wants to keep the engine running properly. Even the same type of motor may require a different oil for its lubrication than that recommended for it by the manufacturer, due to its age or other con-

ditions. ' The dealer or service man who has worked on it can tell what this should be. The choice of oil for the motor should not be left to the man who merely supplies fuel and oil. The advice of the service man or dealer on the subject of oil should be sought at least twice annually, once before, the warm spell and once before the winter season. The automobile especially if it has been run much, may require a heavier oil during the summer than in winter, and only the service man who knows Hie motor can tell just what grade- and kind of oil it needs. Usually a lighter grade of oil is needed for winter because cold tends to stiffen it. Stiff oil means that the pistons scrape along the raw sides of the cylinders during the first explosions of the motor, without benefit of the necessary film to afford smooth operation

and prevent scoring of the walls. II also means hard starting, sometimes so hard that it is difficult for the eleotrio starter to turn over the motor. Too light an oil, on the other hand, even in cold weather, means liability of broken films of lubricants along the cylinder walls when Hie motor has heated up and when this film is needed most for lubrication. It Is therefore very important to know exactly what, grade of oil is best for the car at all season* of the year.” THE BRAKE DANGER. Brakes, too, belong to that small army of motor car components Of which it may be truthfully said In many instances that they “ are out of sight and out of mind.” As long aa the brakes pull up the car on an ordinary road within a reasonable distance when applied hard, the owner is prone to think that they are safe and effective. This, however, is a serious fallacy. Brakes which only just suffice under normal conditions can hardly be considered adequate to cope with an emergency, and too often the brakes which act, “ just well enough ” for everyday purposes will be found lamentably ineffective when it is necessary to pull the car up with a round turn, or to descend some long steep hill.

Brakes which act smoothly and are free from squeaks, but which take unduly long to halt the car, may he found to have oil on their linings. Although the oil does not render them inoperative when they are used to pull up gradually on the level, they will not retard the car quickly in an emergency, and if used on a long hill, the oil will become more fluid as the friction warms the brakes, and so they will become more and more effective, with the result that the car may get out of control. Beware, then, of oil on the brake linings, and keep a watchful eye for it. Next we have the slowly operating brake, which makes a big squeak as it 'goes about its work. This squeaking may he due either to the fabric lining having become heavily impregnated with dirt, or it may be caused by the wear of the fabric being so great that the nietal rivet heads bear against the drum. In either instance, the brakes need attention for whatever the cause, the bands or shoes cannot exert their proper frictional effort upon the drums. Another common brake defect which the thoughtless owner ignores is lack of equalisation—that is to say, the braking effect on one wheel is greater than on the other, From an economic standpoint, this is very undesirable, since its hastens tyre-wear and puts heavy strains on the rear axle* The danger of it lies in the car’s behaviour when the brakes are jammed on when travelling at speed or on a greasy road. One wheel locks, whilst the other spins freely and the car, of course, skids off to one side. The modern wheel is, fortunately, a sturdy unit, and demands little more than an occasional greasing and-the tightening up of its bearings when they show signs of play. Still, it is prudent to inspect the wheels and tub axles fi’om time to lime, making sure that there is plenty of lubricant and shaking the wheel to see that it is Arm on its bearings.