I have heard many a times from other fellow members against fuel/oil additives. With half heart I tried the System-D in my Linea for the past 3 tankful refills. I found that the car is more free revving and sounds more refined. So I am planning to try some oil additives in 2-3 weeks when the time is up for the next oil change. Shell Rimula R4 XADO One stage Atomic Conditioner XADO Vita Flush. ll post the review on this once I try these. Have anyone tried any other additives before? Can you please share your experience as well?