That sludge ONLY accumulates if NON DETERGENT oil is used. High quality detergent oils (with the proper API rating) have been around since at least the early 1950s. That "10%" myth ignores the fact that detergent/dispersants in any oil worth using traps and suspends the "sludge"- - - -which gets drained out with every oil change.
Jerry
Good point on the detergent oil Jerry. My story about the mechanic dealing with deteriorated filter lines and seeing no significant reduction in sludge in the pan whether the engine had a filter or not was before the detergent oil era.
