I don't think the oil tells the story. Every diesel I've owned has inky black oil very shortly after an oil change. Even my diesel tractors. With a diesel engine's inherently higher compression ratio, blow-by is almost guaranteed. And if you look at exhaust after-treatment systems, it's just that. A DPF or a DEF injector have zero affect on the engine. On a Ford, engine regeneration does introduce a small amount of oil dilution via diesel. On a GM diesel, it does not. Nevertheless, oil analysis after oil analysis shows that there really isn't enough dilution to cause a problem. EGR causes coking, and EGR coolers can get plugged up. But EGR coolers are no big deal to clean or replace on a 6.7L Ford, and at $300 aren't that expensive either. Nor do they fail routinely like on some older diesels.

I understand you not liking the modern emissions controls. I don't really like them either...they add expense and failure points. I think they have evolved to a point where they are pretty reliable, though. For me, my main concerns are the fuel system and the major expense if you get water in the system, or some other contaminant.

 

You won't be disappointed.

 

In the old days before diesel emissions, a diesel would far outlast a gas engine. Now with all of the emissions equipment on the new trucks I would say the gas engine is more reliable unless you plan on deleting the emissions equipment on the diesel.

 

 

Good for you, smokewagun. From my perspective, oil in a diesel engine gets very black very quickly, regardless of emissions equipment or not. I'd be curious on one thing, though...if you pull your dipstick after the oil has been in the engine for at least a few hundred miles and sniff it...does it smell like diesel exhaust?

 

Every diesel I have changed the oil in, the oil turns black quickly, that's not a bad thing, that just means the detergents in the oil are doing their job. However an emissions equiped Diesel will have more oil contamination, and dilution, but that can only be tested by an oil analysis not by the color of the oil.

 

 

Get the gas engine and invest the 9k that the diesel will cost. Compound interest is a beautiful thing!

 

 

No ridicule, and I'm sorry if that seemed implied. I have a fair amount of diesel engine experience. I love them, actually. But I disagree that the emissions controls are causing the problem. Think about it...the DPF is the last item on the exhaust system before it exits the truck. It cannot cause more carbon in the oil. Of course, active regeneration must occur *because* there is a DPF...and in the case of Ford, the method is injecting diesel while the valves are on the exhaust stroke. The goal is to send all the diesel down the exhaust system. A small amount of diesel fuel will enter the crankcase as blow-by. But this is clean, unburned diesel. And as for EGR...yes, it is dead end-gas which is sent back in to be mixed with fresh air. It doesn't really burn, just serves to lower combustion temps to reduce NOx. If it blows by the rings int the crankcase it will add some carbon. So in my opinion, only EGR could serve to significantly blacken the oil or make it more carbon-rich. Yet, in my experience, diesel engines without EGR have just as disgusting oil as EGR-equipped engines. I asked about the oil smell because smelling exhaust in the oil is indicative of blow-by. This is the case with every diesel engine I've ever smelled, whether equipped with full emissions or none. Yet gas engines tend to have a more pure oil smell which a much less pronounced exhaust smell. I assume it is because of lower compression. But anyway, that's my opinion.

 

I don't think gas/diesel makes much difference at all in longevity anymore.I'm intending to keep my next diesel for 12-14 years at most. That's about as long as I kept my V-10 F-250. The trouble isn't in longevity of the mechanical components but rather the electronics. I wouldn't expect a computer to work 20 years without upgrading the motherboard and just about everything else inside the case. Support for software just doesn't seem to ever be kept up for 20+ years.

 

Automotive computers tend to be very good because they are quite basic. It is pretty rare for the engine or transmission ECU to fail. Body control modules, and various other modules, however, have a higher failure rate.

 

Even if you take EGR and dpf regen out of the equation a dpf, equiped truck will still be less efficient and have more build up in the oil due to the restrictive exhaust.

 

Not meant to ridicule you but; soot DOES NOT increase engine wear in Diesel Engines. Soot "particles" are normally smaller than 1 micron (usually much smaller) which is too small to cause wear. In fact, while the very best by-pass filter systems do filter more "dirt" out of engine oil than full flow filter systems, they DO NOT remove soot because particles are so small. My primary point = Using the term "dirty oil" to describe black oil is not accurate. Dirt found during oil analysis is actually silicon based (as is most of the "dirt" on our planet) and comes through poor air filtration, and is totally unrelated to soot. My secondary point = Soot does not wear out engine components unless; 1) it is so severe it conglomerates into much larger particle size and 2) and your engine oil filter clogs to the point of going into bypass (letting the large particles through the engine), but we are talking extremely neglected engines (running the oil and filters many times the recommended change intervals.
s lubrication system)

Also, as stated, some engines produce more soot than others during the combustion event. Older per-combustion engines produced more than newer direct injected engines, but when you get new enough to have EGR systems, the soot levels returned back to levels similar to the older pre-chamber engines. The "cleanest" (based on using opacity as the test, which is meaningless) engines are direct injected pre-egr engines (like a 7.3 Powerstroke). My 7.3 Powerstroke oil looks much "less black" than my 89 IDI 7.3.. But that is a meaningless point in judging the oils service life. Many, many fleets are running oil to the point of failure, but even then, its not the soot that causes the failure of the oil.

Oil analysis is the only way to evaluate oils useful life, but it isn't cost effective unless being used to to extend oil drain intervals for large fleets (they don't sample every truck every time). A huge amount of money can be saved by fleets by extending drain intervals to the maximum safe point. For someone with only one (or a few) engines, it is more economical to just change the oil at the recommended intervals established by the manufacturer for THAT ENGINE AND USAGE.

Black oil isn't wearing out your engine unless it has dirt in it.

 

I would mention that one reason diesels have historically outlasted gas engines is that they have heavier duty internals. This is still true today. If you compare a gas 6.2L Ford to a 6.7L diesel, the gas engine has two long timing chains, variable cam timing, tiny little lifters on the end of the rocker arms, etc. The diesel has a vastly larger and stronger crankshaft, massive lifters which drive two pushrods each and have large roller wheels on the bottom, a gear driven single camshaft which is huge, gear-drive fuel pump, etc. Granted, some of this strength is due to the higher forces imparted on the internals...but realistically it is built much more heavy duty than the gas engine.