There is a major point to remember about engine flush formulas...they completely deplete the residual lubricatng film on the metal-to-metal contact surfaces.
Even if you prefill the filter with oil when you change the oil, there is no way to prevent a DRY start; you are going to cause undue wear and tear with unlubricated metal-to-metal contact.
If you use a flush, you shoot yourself in the foot twice! You do succeed in completely cleaning out the engine, but you also cause unnecessary wear and tear!
If you are really worried about deposit formation, try substituting a quart of motor oil with a quart of Rislone. Rislone works over the life of the oil change to clean and hold contaminants in suspension; it also reinforces and increases all the properties of motor oil.
for further information...it will not void OEM warranty!
I just got a 1999 Subaru Forester from my parents (long story) and it has @ 19,750 miles on it. Often times, this car only saw 1 oil change per year due to low mileage; I am going to do an oil change later this month and subsitute 1 quart of Rislone to increase the cleaning ability of the stock motor oils.
TESTIMONIAL: I used to own a 1993 Pontiac Grand Am; I try to use the Rislone at least 2 times a year for a prewinter and postwinter engine cleaner; I changed the oil at my parents house in the summer of 1995 before moving to Florida in August of 1995; the previous oil change done in the spring included Rislone; I put the used motor oil somewhere in the garage; in 2001 on a visit, my father found the container holding that oil change (we both forgot about it and he has lube shops do his oil changes); I took the oil to an AutoZone for recycling and there was hardly any sludge or deposits in the bottom of the laundry detergent bottle that I put that oil change into...even after 6 years, the Rislone held the contaminants in suspension.