ON CLEANING THE SUMP

NZ Truth, Issue 1194, 18 October 1928, Page 20

ON CLEANING THE SUMP

Stipidd Be Prairied and Fresh I^s

S AN argument m regard to the relative merits of -adding oil to that already contained m the sump, and completely changing it, has arisen between two "N.Z. Truth" readers. ,

/"|NE maintains that the best way is \J to empty the sump before adding fresh oil; while his friend declares that it is quite correct to add oil when necessary. "Truth's" motoring' expert has bean asked to' adjudicate. He does so m favor of making ,;a complete change, except m .cases where efficient 'filters are fitted, and even then the . oil .should be completely . changed every 2000 miles at least. ' ' ■.. ' There is really no heed for ah argument jri this case. .•■■■'■• An inspection of the oil itself* will demonstrate the great advantage, of completely changing the oil instead of adding fresh lubricant as the amount m the;, sump decreases. ... - -' ■ W.h&h fresh oil is poured- in, it js of a.; bright color, and, ;.; of course, quite clean. v After* the car has run 200 miles an examination of the oil removed from

the sump will* show- that it is/much darkef m color, probably nearly black,, and contains an appreciable amount of 1 black sediment. ' • ; \ At the end of a few hundred miles the amount of oil m the sump will have decreased- probably by 25 per cent, or more, and that much fresh oil is, required. ■ ' .■■..•. . „,.-■■-. By 'the time two or three lots of fresh oil have been added this way; the lubricant has degenerated into, little better than- sludge. : On th'e other hand, when the sump is drained every 800 or 1000 miles ; and fresh oil poured m, it is obvious- that the engine is working under far better conditions. !v - The more complete the emptying: of. the sump the better, so that it should be done when, the engine is' 1 hot' and the drain plug' left open . for as long as possible.'. c .'■■- . , •'■'' ' ■". •■'•'. •■■:'■