First time I have ever done that! I did about 5 OCs this week and muffed the last one. My buddy bought a 5q of ST Synth and a MC filter for "his" Liberty 3.7 that was at 5000mi on drum oil. I guess it was the combo of two people working on a job instead of one, also I was distracted by other things, plus the old filter gave us a bit of a struggle. I felt like an idiot after pouring in the whole 5q and him saying, "is the plug in?" At least I had some GF-4 Drive Clean to put in that only cost me $1.20/q. I told him, we'd redo it if he got another type oil, leaving on the filter. I feel like a dummy. A laugh at my expense, but also a lesson learned.