“NEW” 15W40 Shell Rotella T Diesel Oil API CJ-4, CI-4 Plus, CH-4, CF-4, CF/SM, conventional (lab tested 2012)
Okay, I see the GF-5 (gas) vs the CK-4 ratings (diesel) having to do with soot buildup (which increases viscosity and shearing) and longevity of DPF and emissions devices. I am seeing differences in the Boron content, but the Calcium is similar, Zinc is lower but we supposedly don't care, so, when comparing the anti soot/sludge additives, I don't see a HUGE difference at all. I answered my own question (kind of), but still questioning it.....
No. The author stated that the reason for the pressure testing is to test how the FILM protects, vs the "hydroscopic wedge" running in between the bearings and the journals. (Which per the author, regardless of weight has the same psi load in that capacity) It has mostly to do with formulation. Some of the lighter weight oils had better pressure resistance which I believe equates to better film protection/shear resistance. I would have to reread the article to confirm that. He also stated the bit about the higher weight oils flowing more slowly, causing starvation/poor flow during cold weather start ups, and, causing higher bearing temps near the rod and crank bearings, thereby causing heat build up and higher sump temperatures. The lighter weight oils flow better reducing heat. I also think he mentioned shearing as less of a problem in modern engines due to roller lifters and OHC designs.
I understand the science behind his testing, however I have seen first hand excessive wear on internal engine parts and major engine overhauls needed due to lighter weight engine oils being used in diesels. Cam lobes almost completely ground flat and bearings from rods and main bearings being worn extremely bad. The author of this article has good science behind his findings, however for a Diesel engine application with extended drain intervals such as we run in the Ecodiesel I don't trust the lighter weight oils at all. Especially if they're not Diesel engine approved.
You really seem to be on one, you go ahead and run what bob the engineer says to run in your pickup because what he says is gospel. The lighter weight oil that was used in the engines in question was Rotella T5 10w-30 which is a Diesel engine oil Records and oil samples were taken throughout the engines life so it wasn't like nobody knew what was happening.
That is NOT what I was advocating. I clearly stated I gave that up after further research and consideration. Bob the engineer(as you call him) has clearly shown Empirical Data to prove what he is saying. If you want to get all up in your emotions and cling to the old standards, go for it. Was only stating what was PROVEN in his testing. He also shows that Rotella (sacred cow?) scores lower in his pressure ratings. I guess that ticks you off because it is flying in the face of everything you know???
I personally really dislike Rotella, it is no sacred cow to me I think it's over rated garbage in a bottle. That being said it meets a spec and it's what our vehicle manufacturer recommends. That article actually proves nothing other than some pressure testing and a small glimpse into the oils additive packages. The only way to know how any of those oils would perform in a Diesel engine application would be to have years worth of used oil analysis done across a broad spectrum of engines. The article doesn't go against anything I know. It also doesn't prove which oil actually protects, it only shows what oil should protect when it's brand new based on a single test. It doesn't show how well an oil sticks to internal parts after an engine is shut off, it also doesn't show how an oil works 5k miles into a service interval or how the TBN holds up throughout the life of the oil. I'm more than willing to have a good conversation about oils, but I don't think basing my knowledge of oil off of what one guy says would be my source for all my responses.
This ONE GUY is the only one who does tests like this. His pedigree speaks for itself. He actually DID do some tests on oils with 5k miles on them and also explained quite a bit of why he believes the tests he performs are quality tests that actually DO corroborate real world results of engines using certain oil formulations. He also did the tests under a normal heat range and excessive heat. Too bad you got "bored" and quit reading. Maybe instead of beating me down about the Science of his blog, you should go back and read it. It most certainly DOES prove which oils have the best film/protection offered, rated from best to worst. I am seeing that this conversation is like Religion and Politics. Some people will not be open to information that they do not agree with.
I did go back and read the deal. I'm not beating you down about the science of his blog, I'm telling you not to put all your cards in his basket. I do find it funny how you bring religion and politics into it like it's a bad thing, like a character flaw of my own, yet you're the one who read something and now believe it to be gospel and won't open yourself up to the thought that the guy might potentially be wrong. After reading some of the Q&A's they guy flaunts his mechanical engineering degree like it's something that puts him on the same level of intelligence as Einstein or Stephen Hawking. He offers very vague theories on why all diesel engine oils, other than the gas/diesel Euro spec oils perform quite poorly in the pressure test. I'm asking you to do more research on diesel engine oils, do not look at his blog for advice on diesel engines, it's clearly geared mostly towards gasoline vehicles. Utilize tools such as Bob is the Oil Guy, or the old google search function, or maybe get in touch with some oil engineers. Almost every diesel engine I've been around to date calls for either 15w40 or 5w40 DIESEL ENGINE OIL, my ford 6.7 came factory filled with 10w30 Diesel Engine Oil. None have come factory filled with Quaker State 0w20 or any gasoline engine oil for that matter. Here's a quote from another oil expert that might actually know what he's talking about, rather than stating some gas and diesel engine oils have similar additive packages, so they should be interchangeable.
