CYLINDER WEAR.

Hawera Star, Volume XLVI, 12 February 1927, Page 11

CYLINDER WEAR.

CHANGE OF OIL NECESSARY. Wear of automobile pistons after 2000 miles running of the car averages between one and two one-thousand of an inch, according to figures compiled by the American Research Foundation. ‘ ‘ Original clearance in a now engine is from three to four one : thousandths of: an inch,” the bulletin states. "After running 2000 miles the space between the piston and the cylinder wall is increased 40 per cent. For economical running of -the engine and preservation of the life of the car an entirely different grade of lubricating oil must be used from this period on. "Wear inside the cylinder is constant, and the grade of oil must be changed again after 10,000 to 12,000 miles, when the clearance has increased to 100 per cent, more than the original space.”

While the figures may be accepted as general experience, it is impossible to lay down a definite rate of wear for all engines. There will be differences according to whether aluminium or cast iron pistons are used, and a high speed motor must receive more wear through the additional number of piston strokes for a given mileage. If laboratory tests are accepted it seems certain that air filters will greatly reduce wear, while it must not be forgotten that thinned oil will increase friction.