Really dark oil - CG 0w30

Joined
May 8, 2009
Messages
14
Location
Pennsylvania
I just changed my friends oil, he has a 2004 Cobra and ran 6.5qt of GC after running RP 5w20 for the last 2 changes. He always uses a Motorcraft filter The oil had about 4,000 miles on it and was VERY dark coming out. Does this mean it did a good job cleaning or is there something wrong?
 
Joined
Aug 21, 2008
Messages
25,051
Location
ON, Canada eh?
You can't judge and oil by it's colour. I have UOA's that show me my oil is spent and the oil is still a nice golden colour on the dipstick then I have others that the oil is very dark within a few thousand miles but the UOA's say it's suitable for continued use! ;\)
 
Joined
Aug 21, 2008
Messages
25,051
Location
ON, Canada eh?
In most cases yes. If it was a milky brown colour then you have a coolant leak into it. If it's a thick dark brown colour and feels like a paste, then it's a sludge issue. But if it's just "dirty" looking dark then it doesn't mean much. UOA is the only way to tell how well the oil is doing and how much time it has left. ;\)
 
Joined
Oct 18, 2007
Messages
3,756
Location
CA
The only way to tell is to run it a few more times. When I switched to the Amsoil ACD even though the car had relatively low miles, it got dark quickly. It wasn't until the third or fourth change that it stopped doing that. Now it stays pretty much the same out to the 5,000 mile interval, barely darkens at all. The only resonable explanation was that it was doing some cleaning at first. Edit. I forgot to add, nice car! The '03-'04 Cobra is what I'll probably buy after my TL is paid off..... Just what I need, another toy.
 
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Joined
Jan 22, 2003
Messages
1,676
Location
Waldorf, Maryland
I use Mobil 1 in all my cars. I have found that it gets dark colored fast in my cars with an iron engine block. My cars with an aluminum block stay honey colored for a LONG time.
 
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