Prabhakar & All,
I believe in your post, by profession I am a Reliability and Maintenance consultant here in our country and one of the courses I teach is lubrication and contamination control. I do not want to speak more of this as to comply with the forum rules and guidelines.
As far as my estimates will go, around 90% of the population will change oil based on the running hours their car, equipment had been in service since this is the way of doing things.
Oil must be change not based on the running hours it had been in service but by the number of contaminants your oil have and this will reflect the acidity of your oil (TAN).
Now for engine oil, is this possible, yes, but if your equipment is equipped with what you call a by-pass filtration (secondary filtration) with a high beta rating 200 or more, say from 1 to 3 microns in range plus a regular oil analysis check from time to time in order to achieve an extended drain or indefinite oil drain interval. Now a lot of brands of bypass had been seen on the net most specially in the US, why, because it had already been approved by their congress as a means of energy conservation act.
Now if your consider the cost of oil vs the cost of your by-pass and oil analysis check then definitely the latter (bypass and oil analysis) will be much more expensive than the cost of oil itself.
But if you consider the dear life of your engine and the breakdowns you encounter plus engine overhauls after 100,000 200,000 running hours then this is were the Total Life Cycle Costs had been achieved.
Cheers,
Rolly Angeles