One of my positions was working for a large Transportation Company (largest in US). They have a fleet of over the road rigs and trailers. They were totally dialed in with Total Quality Management and did extensive research on oil, Synthetic and Dino and correct interval. Substantial data developed through oil analysis, engine wear and driving habits. All equipment was dialed into computer system monitoring run time, run speed, idle time and MPG.
What they found..........Synthetic is best. These where large truck diesels so needed minimum idle time after start and after a long run. Enough to cycle engine oil through the filter system removing any metal particles and most important acids that developed via the diesel compressed ignition process. At the time of my leaving, oil change intervals were at 50K per unit. This was monitored and happened religiously through extensive countywide maintenance network. It was common to have power units run normally without any engine issues at over a million miles.
Now to gas engines and our cars. We don't have the worry of acids in oil to extent a diesel engine has, but same principle applies. Start-up and minimum idle to start oil flow and full engine lubrication...about 1 minute. End of long run-idle for about a minute to have oil pass through filter. Then shut down. What kills our engines is the stop and go runs without engine getting to full operations temperature. Allows moisture to build up in engine and exhaust system. Today for example, left house at 7 Degrees and engine and vehicle didn't reach normal operating range for 20 minutes-15 miles of this on interstate.
I used to be a 5K oil changer fanatic. Now I take the time to ensure proper vehicle operations getting to normal operations temp and appropriate shut down. My T4R just rolled over 20K today and it does not use a drop of oil. My dad had two T4R's a 2nd gen and a 3rd Gen. He was brutal on them towing a bass boat all over the northeast with hard acceleration from stops. The 2nd Gen was a 4 cylinder and the 3rd Gen the 3.4 V6. Both ran flawlessly, the 2nd gen had 250K when he traded it for the 3rd gen. The 3rd gen had 160k and outlasted Dad. Only failure was electric antenna needed replacing.
To each there own in terms of comfort level with oil changing interval. Proven research has shown not necessary at low mileage intervals if you take appropriate operations steps.
My two cents
Regards