Motorcraft 5w20 Synthetic Oil Question

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Apr 13, 2009
Miami-Dade County
I bought my 05 Ford Crown Victoria with 20K miles on it at the end of 05. It now has 75K miles. Up until 50K miles I was using 5w20 Motorcraft Blend. Then I switched over to 5w20 Motorcraft Full Synthetic. I change out every 5K miles. I notice though at 5K miles the Full Synthetic is allot more dirtier then the Blend. The Blend would be a median brown where the Full Synthetic is a very dark brown though not black.

Is that anything to worry about or is it darker because it cleans the engine better? BTW I never have to add between changes on the Blend or Full Synthetic.

I am hoping to keep the car for at least 200K miles or more like I did with my last car which was a 98 Crown Vic. The 98 used 5w30 Regular Dino Oil.
My 96 Grand Marq. has 210,000 miles and I do 10,000 mile OCIs. I use M1 10-30 and 5=30 and the oil color goes to a dark amber, but the engine is stays very clean.
Fully synthetic oils tend to have higher detergent levels, which can be directly related to the darkness of the oil since it may be cleaning out varnish or sludge. It may eventually come to a point where it doesn't darken much.
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