6500 miles on my 2007 Sportage oil (75% Mag1 Fully Synthetic + 25% Mag1 dino oil). I do an oil blot test and after 30 hours, I see a nice homogenous medium brown inch-wide circle of dry oil on the card. And a clear, colorless halo 3/16 inch around it. What is this halo about and what does it mean? Sorry guys, no pictures taken.