Anyway, I've been pleased with the UOAs I get from Motorcraft synblend and the Quicklane service. But I saw jugs of Castrol Edge EP for cheap at WM and I somewhat impulsively bought it. As we all know, products that come in gold colored jugs are the best. Also, I was hoping I could get a solid years' worth of service out of the oil. The MC would be pretty close to failure at 9K. An extra 3-4K would be good. Anyway, the engine (3.7L Ford) was noticeably quieter with the new oil. I'm about 95% sure it wasn't just my imagination. What causes this? Does this signify that it's lubricating better? I figure unless it's out and out consumer fraud, the Castrol Edge EP ought to make it to 13K, (although I'll UOA) But what makes an oil 'quiet'? About 85K on the unit, in good condition.