The green color is a break in oil additive.I have never did the first break in oil change on a GM vehical.But I have seen this on small engine like Kohler.First I thought Oh no antifreeze in the oil.Until I realised the Kohler was air cooled.GM uses the pink antifreeze so your also safe.

Also when you change oil the first time.Its normal to see a metalic grey color and resembles graphite.Thats the filings and is normal and the green additive is to help remove them.

The oil filter was tight because the factory does not put a small film of oil on the seal and also the filter base plate is dry and oil free at time of filter installation.

Im not sure what oil they use at the factory.But GM Goodwrench oil I think is distributed bottled from Valvoline oil.

Fresh oils do vary in color. For example, Pennzoil is darker than the average.

I used to use Kendall GT1 Oil all the time. It was green, looked a bit dirty when brand new. Was recommended by one of the high performance cam makers otherwise no guarantee for wiped lobes. Apparently contained higher than normal levels of something like zinc/phophate high contact pressure - anti wear stuff in the additive package.

Last couple of time I bought it, its now typical golden yellow color. Newer oils have less zinc for polution reasons over the past 3 yrs or so and during that same 3 yrs many aftermarket cams manufactorers are seeing worn lifters and cam lobes and some suggesting an additional bottle of an added anti-wear additive with the oil change.

Oil for diesels starts brown like other oils, but turns black very quickly as it keeps soot particles in suspension.

Thanks for the great input/information.

Speaking of different oils, I purchased a gallon of Shell Rotella Heavy Duty SAE 30 motor oil at Wal-mart for use in my air cooled yard and garden tractors as well as other small air coolded engines. On getting home I give it a close look and see it is API rated: CF-4, CF-2, CF/SJ, or an oil for diesel engines (mostly). But as it carries an "SJ" rating I assume it is good too in gasoline engines. Any comment?

dont know what kind of oil the dealer uses, but its lite gold when they put it in and a yr later or 6000 miles, when i get it changed, its still lite gold.

Used to be six months, change oil - otherwise something starts to go acid & starts eating away bearing coatings.

(imagine that! - Rotella diesel oils in both full syn and dino is one of the oils recommended by cam makers because it still contains a good amount of zinc and other good antiwear things)

Pretty much any oil that is rated for use in a diesel engine can be used safely in a gasoline engine -- at least in four-strokes. I will defer to the group's greater knowledge about two-stroke engines! :-)

Sounds like we have a sale, I'll follow my original plan and use the Rotella 30W in my 4-cycle utility gasoline engines. I did buy the dino type. I haven't yet taken the step to synthitics.