I was using RLI Biosyn for a while, and then I ran out and needed to do an oil change (6 months+) maybe not needed - but wanted to. After letting it drain as thoroughly as possible, I put in M1 Synth with about 1/2 a bottle of ARX. I forgot that the recommendation is to put in a full bottle on Dino oil.. and a few ounces for maintenance aftewards. I stopped before hitting 1 bottle. Does it make a difference? I just did a purge of about 3 quarts and will send the oil for analysis... Still some ARX in there, but limited quantities.