The test was set up to check engine protection, fuel economy improvements and the suitability for extended oil change intervals when using fully-synthetic engine oil. Each car on the fleet completed 100,000 miles. Three were lubricated with the fully synthetic oil Mobil 1 with 24,000-mile oil change intervals, the rest were run on 12,000-mile oil change intervals in line with Saab's recommendations, with either mineral oil or Mobil 1.
Even with an oil change interval twice as long as the recommended period the three synthetic oil lubricated engines showed only marginally more wear to the connecting rod bearings, oil pump, camshaft cam followers and valves than the 12,000-mile oil change cars. The chauffeur company said the overall condition of the engine was described as good and suitable for further service.