A Field Test Study of Camshaft Wear in a 2.3L OHC Engine and Its Correlation to the Sequence V-D Test

A field test was conducted to evaluate the valve train wear performance of new technology crankcase lubricants in 1980 vehicles powered by 2.3L overhead camshaft engines. Three SF/CD 15W-40 oils and two low phosphorus SF/CC 10W-30 passenger car oils were evaluated in commuter service with extended oil drain intervals for 48,000 to 80,000 km. interim wear measurements of the camshaft lobes and camshaft followers were performed throughout the test.

All five of the new technology lubricants tested demonstrated good control of valve train wear in this service. These oils also passed the V-D test, thus, the test supports the use of SF wear limits in the V-D test for defining passenger oil quality levels. Wear profiles indicate that camshaft wear rates were significantly higher during break-in and were not particularly sensitive to oil chemistry during break-in. Oils formulated with secondary alkyl zinc dithiophosphate (Zn DTP) wear inhibitors provided significantly better wear protection than two different primary alkyl Zn DTPs. A secondary alkyl Zn DTP demonstrated good wear protection at phosphorus contents as low as 0.07 per cent (w).