Drain -Flush-Re-Fill.''

" Drain—Flush—Re-Fill."

THE motorist to-day has been so well educated as to the desirability of draining the used oil from his crankcase and replenishing with fresh oil that the phrase Drain, Flush and ReFill" has almost passed into everyday use.

In many cases, however, the benefit derived from the insertion of fresh oil is to a large degree marred by inefficient flushing. At one time it was believed that the best way of flushing was to swill paraffin through the engine, in order to remove sludge and dirt from the oilpassages and interior of the crankcase.

It is now known, however, that although it may remove foreign matter, paraffin itself has a detrimental effect on the engine. For one thing, it actually rusts the metal • for another, it tends to clog the small oil-ways, etc., and to prevent the new oil from entering them. The resulting damage, of course, is incalculable.

The failure of paraffin to perform the work has led to the introduction of a fluid known as flushing oil. Various makes of this are available, and most garages keep it in bulk for use on customers' cars ; one firm, also, for the convenience of owner drivers, is retailing it in tins.

To use a flushing oil, drain the crankcase—when the engine is warm so that the oil flows more readily—and re-place the plug. Pour in the necessary quantity of flushing oil and start up the engine, allowing it to idle for a short time ; this will do no harm for the flushing oil is a lubricant as well as a cleanser. Then drain the sump once more and the engine will be spotlessly clean and ready for the new lubricant.

The Importance of Spring Strength.

SOME manufacturers make one type of chassis which is fitted, exactly as it stands, with a two-seater, four-seater, or saloon body as the case may be. The very widely differing weights

of these bodies, and of the human freight likely to be carried, are not taken into consideration.

The makers of Rolls-Royce cars go to the other extreme, for not only do they spring the chassis according to the weight of the body—they also carry out chassis tests with a weight equivalent to that of the actual body which is to be fitted.

When a chassis is nearing completion, the coach-builders who are making the body are called upon to declare its finished weight. Springs varying from light to heavy, according to the weight of the body, are then fitted, and the chassis goes through its prolonged tests. After it has passed a veritable army of inspectors, it is delivered to the coach-builders.

If the estimated weight of the body is found to have been inaccurate, the chassis is re-sprung—and the coach-builder is charged with the work. So extensive is the company's organization indeed, that inspectors are sent almost anywhere in the world to make these final tests.