Ace! said:
Maybe diesel engines used to be far more reliable or require less maintenance, but it is not necessarily the case today. Ford for example built the V10 engine engineered with a 400k mile service life, typically in fleet or commercial applications. It requires less maintenance than the diesel and is lighter in weight (offers higher payload in similarly equipped trucks).
Not to get into a pissing contest Ace, but, I'm not sure where you sourced the data to make the statement in your first sentence. My wife's uncle owns several Ford dealerships. We were just talking about diesel engines over Christmas. Labor hours expended per unit and recorded maintenance visits to southeast dealerships for E/F-150 and E/F-250 gasoline engines far exceeds ALL Ford diesel motor variants combined installed in all F and E models! Including the problematic 6.0. Which was a design issue. And this is not to imply Ford gasoline engines are problematic! Simply, per unit, gasoline engine trucks and vans require more visits to the maintenance department than Ford diesel engines.
Other then preventive maintenance (oil, filters, batteries, hoses, etc) and not including upgrades (suspension, rear bumper, Bully Dog chip, etc), I have spent a grand total of $32 dollars out of pocket for a single engine mechanical problem that developed while driving along in my 2003 F-250 7.4 Super Duty. I perform scheduled maintenance on or before recommended miles. I generally do not wait for parts to fail before replacing same. Every part installed on every vehicle has a MTBF (mean time between failure) value.
Having said that, I am about to replace some more factory installed tired parts. Is there a problem? Nope. But, better to have fresh parts before beginning a long Baja trip.
And why don't I drive a new Super Duty purchased from my wife's uncle? I have 97,000 miles on my 2003 7.3. I have installed countless upgrades. The truck drives like a dream with the Old Man Emu suspension. While I would like to get better MPG (7.3 MPG suffers with ULS fuel), I'm not to the point where I'm ready to write a check for $65,000 for a new F-350 (my next truck) with diesel fuel currently priced at $1.85 in NC. Perhaps when the Ford beer can technology is put into the Super Duty. I keep throwing my money at motorcycles, not pickup trucks.
The best diesel engines? Probably Mercedes Benz. Austro engines are derived from MB diesel truck engines and installed in the Diamond DA-42 (twin engine) airplane. Exceptionally reliable engines and a great airplane to pilot! And one that literally sips fuel consuming a total of ~12 G/H at cruise, both engines combined!