Assuming your E430 is like every other vehicle I have ever owned and/or checked oil on (which is a lot), the difference between the high and low marks is 1qt. I believe this is the case even on my 4.5 - which holds 8 quarts. If it's at the low mark and I add a full quart, it's sometimes slightly over the high mark.
Therefore, you've not even used 1 qt in the time between oil changes.

If your consumption of oil between changes is less than the difference between the high and low mark on the dipstick (not the bottom/end of it, just the low mark) then I wouldn't give it a second thought.

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Back in the saddle - 1972 280SE 4.5