I have 2,000 miles on my GC Gold. I just checked the oil level last night and added .4 of a quart. The oil was still golden. I've had Mobil and Amsoil in for 5k and it hasn't darkened.
I wonder if the oil color has to do with how you drive? I drive pretty conservatively. Also, I've never had an oil in my vehicle longer than 5,000 miles. So it has to be pretty clean in there.
Unlike my parent's minivan... I thought I'd look inside their engine bay and took off the oil cap. It had a layer of grease/filthy oil on the cap that smelled like burnt oil and this red rust stuff inside the engine coating everything... The engine does have 130,000 miles but it goes 5-6k on Quaker State.
To answer your question: Only a UOA (Used Oil Analysis) will tell you if your oil needs changing or not. Oil color really doesn't tell you the state of the oil. But peace of mind is something worth paying for. GC Green should EASILY be able to go 6,000 miles without a problem. If your engine is turbocharged I would change it more often. It definitely wouldn't hurt to change your oil - especially if it looks used.
[ March 13, 2006, 01:34 PM: Message edited by: OriginHacker21 ]
I wouldn't be concerned about the color of the oil, it is quite meaningless. Also, what is the "density" going to tell you? I am not sure of the relevance.
Do a search in the UOA and this forum, you will find many people discussing change intervals including some with Saab and actual analysis.
I can't think of one application where I would do less than 5k-6k miles on GC .
I see no harm in changing your oil at 3,000 miles. Although that would be the earliest I'd ever change synthetic oil (German Castrol Green/Gold). Peace of mind pays for itself... I'd rather sleep at night than use oil longer.
I don't know of any tests that you can do. You can try wavinwayne's idea of putting it on a white 3x5 card to see if the oil has any dirt/contamination in it. If it is dirty, change it right away. Otherwise, the dark oil is doing its job.
Want a cool site that talks about long oil change intervals? Check out: http://neptune.spacebears.com/cars/stories/oil-life.html
They used Mobil 1 and Amsoil past 10,000 miles and did a Used Oil Analysis step by step along the way to see what was going on with the oil. Many interesting facts! Scroll down for the actual tests.
A 3K OCI is a waste of this precious nectar! It's a long-life oil (BMW LL-01) after all! I change mine once a year or 10,000 miles, whichever comes first. UOAs have determined that GC can easily go 10K miles in most applications.
I agree - 3k would be early. If you are really worried go to www.blackstone.com and do a UOA with your oil to know for sure what is going on inside your engine. Otherwise going 6k seems safe and not too wasteful.
I know how you feel though. I am already having a hard time sleeping with my oil in my car past 2,000 miles. If oil was free I'd change it every week just for fun. But it is a good thing I don't because I'd get bored of it pretty quickly.
Right now, on the G35, for wty purposes, I change it when I feel like it between 5k and 7.5k miles. Once the wty is up, I'll adjust to an interval suggested by UOA, which I predict will fall out at around 10k. In the wife's Sequoia, a short tripper, I'm probably going to settle out at one year intervals, though I might make it nine months (safety margin) based upon what the next UOA says. If I had a turbo like pscholte, I'd go shorter too.
Don't fret over color do at least one UOA for yourself so that in the future, you will believe that the darkening is not harmful. You're not talking quickly smut black like a diesel, are you? That might be cause for some concern, and not about the oil.