What color is your motor oil?
It has been my experience (mostly with Castro oil, but I have used many other brands) that fresh oil is a light amber color and used oil is dirty/black.
Today I changed the oil on my 2005 Chevy Colorado (2.8L) for the first time, meaning it had factory oil in it, Delco I assume. The oil had just over 2,000 miles on it and it was dirty, but not dirty black, it was dirty green.
Anyone else seen green oil? Or, does this indicate some kind of a problem?
I note too that GM put the filer on a lot tighter than needed, lucky I had the filter "socket" that fit and could use my 1/2" drive to break the filter loose. I first tried a simple plier-type filter wrench, and it tore a hole in the filter without breaking the seal. Another anomaly, I think, I had trouble getting the after-market Fram filter to start treading on. I tried several times with no success. I then examined the filter side-by-side with the GM Delco filter, looked the same, so I tried again and on it went. Must have been me, not being able to get the filter lined up.
To Chevy's credit the oil flter on this engine is very accessable and they even enstalled an oil drain catch with a pitcher type end that collects and directs oil coming out around the filter's seal face down directly under the filter, where I had set the oil catch pan.