When the US military switched all their vehicles to detergent oil in the mid-1950's they developed a protocol for making the change which involved 2 or 3 short-interval oil changes to flush any accumulated sludge out. For mileage-based vehicles with an odometer, I seem to remember the change interval was 750 miles for 3 changes. For hour-based oil changes, I think the change interval was 10 hours for 3 changes.
The advice about not using detergent oil in engines without a filter, or with a bypass filter is sort of an "old mechanic's tale"- - - -the automotive equivalent of an old wives' tale. Another one is "keep an overheated engine running while adding water" That one went out of date in 1928 when Ford put a water pump on the Model A.
Jerry
