Hi All! As you can see, I'm fairly new here. I've been hanging out a while though, and feel that I'm starting to become addicted. For instance, I went in search of GC last night, eager to try it and despite the fact that I'm not due for a change and have a bunch of Mobil 1 on the shelf (which I've been very happy with, BTW). I found the GC at the AZ right down the street from my house. It was buy 5, get 1 free. The price worked out to about $4.16/qt. Not too shabby, I thought, and good luck, too. Also, they had exactly 6 quarts, go figure. Now for my question. I've always been a die-hard 3k changer, even with the M1. Nothing too good for my baby, you know. I'm starting to see what a waste of money and oil this is, however, and would like to extend this out, but am not sure exactly what approach to take. The options I'm considering are: 1 - change at the usual 3k and send a sample for analysis, then change based on the recommendation and send another sample 2 - wait for the "change engine oil" message to appear (I've got a 2000 Monte Carlo SS with the GM engine oil life system), send a sample, then do the next change at the lab-recommended interval, then send another sample 3 - pick an interval, say 5,000 miles, then change and send a sample, then, change a lab-recommended interval and send a new sample 4 - grab a sample at 3k without a full change, top off the oil, then change it at the interval recommended by the lab. Of course, I'm open to other options too. Any thoughts?