I am the king or Poor Maintenance here on FTE.

My 2007 E350 v10:
-bought in 2013 with 113,000 miles and unknown history
-325,000 miles now (it’s been sitting for nearly a year<more details below>)
-averaged 12-15,000 mile oil change intervals
-air filter about once a year
-fuel filter : replaced one in over 200,000
-original spark plugs replaced at about 300,000 (detailed story and pics here on FTE!)
-strongly suspecting original coolant for the entire 325,000
-front end grease jobs 3-4 times

last year she starting running a bit rough and was a smidge low power, and my need for cargo volume diminished so I parked it. A few months later I put a scope in the cylinders and found coolant in #5. Disassembled and found 2 tiny pinholes in the cylinder head. I got a used head, and had it rebuilt. Valve job and guides and seals and light surfacing for $350.

I had the one head done so I figured I might as well do the other one- especially after filling the ports (before the rebuild) with water and watching it QUICKLY dribbled past the valve seats. So I had the other head serviced. Now it awaits reassembly (anyone in central Florida want the job?).

Ok im way off track- my original point was how good the inside of the engine looked. No caked-up oil, no black spots, and almost no wear on the cylinder walls.
To be completely open- the engine used about a quart per 1,000... so during my four years (200 weeks) of driving it a thousand miles per week, I was basically “changing” 1/6th of the oil every week. The oil on the dipstick always looked golden perfect color clean. But still- I don’t think I ever did an oil change less than 10,000 miles, and it wasn’t remotely uncommon to go 15-18,000 miles.