Originally Posted By: George7941
I have absolutely no proof that the sheared oil adversely affects The HUEI system. But I have come across many instances where Cat engine owners and Cat mechanics recommend oil change intervals to not exceed 6 to 8k miles on HUEI equipped engines, so that is what I have been doing.
Keep in mind that the HUEI system is only a small part of the entire engine, so wear in the HUEI system might not produce big wear metal numbers in a UOA.
I suspect the "recommendations" you get are based on nothing more than a fear of the unknown. That "unknown" being the presumption that vis has a direct relationship to HEUI systems wearing out. I've never seen any data to prove this relationship exists. I think the common factor is one of the mistaking correlation for causation. It kind of goes like this:
- thicker lubes are, and most certainly have been previously, the predominant grade of choice
- HEUI systems have had some history of wear failures
- thicker lubes do shear down with HEUI
And so people presume that correlation of shearing must be causing the wear. However it is completely unproven to be true.
Don't think of shearing being the issue; just think of grade itself. If thinner grades were a problem, then all HEUIs would exhibit the wear issues. But that's not the case.
In the PSD world, there are some folks who have faithfully used 10w-30 and have never had HEUI issues. Of note is RR1, but he's not alone.
On the opposite side of things, are we to believe that folks who've religiously changed 15w-40 at shorter intervals in their C7 have never, ever experienced HEUI failure? I think that's absurd to assume as well. IOW - if you did change 15w-40 often, are you 100% assured that you'll never have HEUI problems?
I agree that the wear from the HEUI components will be so low that even if there's a problem, it probably won't be easily seen in a UOA. However, and I admit I'm not intimately familiar with the C7 HEUI system we discuss here, what specifically is the failure mode of HEUI anyway? Are the issues similar to PSDs?
Here's a list of the common HEUI issues in the PSDs (7.3L and 6.0L)
- broken springs (nothing any grade of oil will cause nor stop from happening)
- poor connectivity (top end signal loss via bad/broken wiring looms or coils in the injector circuit; again no oil is going to cause or alleviate this)
- stiction (a thinner grade here can only help, not hurt)
- HPOP failure (typically a seal that goes bad as the pump really does not wear out, but fails to provide full pressure; this causes hard starting and poor idling)
- HEUI driver failure (in a 6.0L Ford, it's often referred to as the FICM; typically fails in the control unit due to heat/stress cycle failure; nothing to do with lubes)
And don't forget that all injectors do wear out eventually; it's not like this is an unknown phenomenon. Heck, every major city has at least one diesel injection rebuild service. Old IDI systems had wear, and they had the benefit of HIGH sulphur content. Common rail systems eventually wear out their pumps and injectors. CP3 pumps wear. P-pumps wear. Dmax injectors wear. Nothing lasts forever. The best thing for long life of pumps/injectors is clean fuel, and in the case of HEUI, clean oil. I've seen no evidence that thick vis will make a HEUI last longer.
What I'm saying is that rhetoric can run long and deep, and assumptions that are made end up turning into garage maintenance practices.
I am more than willing to accept that grade may cause HEUI issues, but I'd want to know the SPECIFIC mode of failure, and see DIRECT proof of how causation takes place in regard to vis.
Until then, label me a skeptic.
I understand your concern; you want a long, healthy run for your C7. Everyone wants a good ROI with long life from their equipment. And so, you've stuck with what you've heard; the mythology is that vis loss causes HEUI issues. I'm not taunting you; rather, just wanting to have you either be able to prove to yourself that the information you've heard is true, or false. Set emotion aside and look for the existence (or lack thereof) of real proof.
Next time someone tells you that vis drop causes HEUI failures, ask them to be very specific and state what component failed, how it failed, and why vis loss caused failure. If they cannot express this in a logical sense, it's just hooey.
You've got to decide if the smoke from this fire is legitimate, or is it just some darn foolish arsonist fanning the flames of ignorance, perpetuating the regurgitation of countless rumors?
I'm not saying what you claim it wrong. I just have never been convinced that it's true. The proof of data, and the logic of sound principles, is completely lacking.
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