After reading some of the posts about Rislone and Marvel Mystery Oil (never used either) Rislone VOA I decided to try some Motorcraft 5w-20 as a flush. It seems this should provide all the benefits of a lighter oil (cleaning the valvetrain) while having better detergent and AW properties. FWIW I have already done an Auto-RX treatment in this engine. Well, I did it in my 98 Nissan Frontier (4x4 with KA24DE, 5-speed, 65,000 miles) for 300 miles. This motor calls for 5w-30. I filled the crankcase with the Motorcraft 5w-20 (boy does it pour thin). I thought this would be the ideal time of year to try this as it has been cold as h*ll. All of my driving during this flush was highway and I was careful to not lug the engine. See TooSlicks UOAs from his Toyota 2.4 liter engine. 5w-20s in a Toyota My impressions: On the positive side the truck seemed to start very easily in subzero weather and the throttle response seemed quicker. On the negative side the timing chain(s) noise was far more noticeable. I used the Nissan 15208 9E000 filter for this test. If I had to do it over again I'd probably choose the Pennzoil 5w-20 as it has a decent batch of moly. I have changed back to GC 0w-30. There were no symptoms or problems that I was hoping to treat, I just felt like experimenting. What do you think of this practice?