Originally Posted By: Solarent
Where the input does matter is for the rest of the ROI equation; looking at operating conditions, depending on choice of OCI length, desired fuel economy benefits and so on. My point is that the grades all have relevance on on selecting the best oil for your application. Price of the oil, availability also factor into the COST calculation of choosing an engine oil.
I fully support this approach:
Originally Posted By: dnewton3
Make an informed decision: first consider your operating conditions, next determine your maintenance plan, and then pick your lube and filter. Don't do it the other way around
Then perhaps we are more aligned that apart.
I completely agree that ROI based upon fuel economy, cost of product, etc makes a big difference.
And in fact, if you go back to my first answer in the thread, I said that I'd buy the least expensive one, because when wear traits are assured (as is the typical case in the real world, as well as the premise of your question), then factors OTHER THAN wear are the deciding issue.
But VIS isn't the trait I care about. It is, after all, an INPUT and not a RESULT. You are still speaking about things from a perspective of inputs.
When I shop for a fluid, I consider this approach:
I need a lube that is API qualified for my application, will last the duration of my intended OCI, and is easily attained for the least cost while supporting the best ROI in operation. For any specific application, I then sort the wheat from the chaff. For my Dmax, I choose CJ-4 dino oil. The reason I use 10w-30 is not to save fuel, but to prove it's viability compared to the traditional "thicker" lubes. I cannot find a true tangible savings in fuel; my low annual mileage would never show any real disparity. However, large equipment companies (mining, OTR rigs, etc) can certainly make the tiny savings turn into big money.
Similarly, my two MGMs with 4.6L mod motors simply don't care about vis when it comes to wear, but it does matter likely in economy, but only with BIG jumps in vis ranges. It's proven that the mod motors can run as well on 10w-40 as 5w-20 in terms of wear, but the thinner grade is going to get you a better fuel result. However, the distinction is nearly unnoticeable if you're taking about the challenges between 5w-20 and 5w-30. And if you're in a warm climate, even a 10w-30 may be hard to distinguish from the thinner lubes. Singular vehicles operated with relatively low mileage (20k miles or less) are hard to quantify fuel rates, versus big industries that consume tens-o-thousands of gallons per year.
So maybe we are closer than I had thought, but I still perceive that you're hung up on the inputs, whereas I care more about the results. I first define what I need the fluid to do, then I go find one that works. I don't select a vis, and then worry about how it may or many not fit into my regime. I am not saying vis isn't important; it is. But it's not something to focus on, but rather to use as a means to get to the end. The end-goal should be a satisfactorily low wear rate combined with lowest cost operation.
If someone gave me cases of 10w-30 to run in my cars, at no cost, I'd use it because the loss in fuel economy would pale to the savings in free lube. But if the costs were near-identical for lube (such as ST 5w-20 versus 10w-30 at Wally's), then the fuel savings outweighs the lube cost differential. This is, quite literally, dependent upon each and every single variant you use to judge the ROI. Because I know the wear rates are unaffected by the lube grade, then COST is what I use to make my decision. Hence my very first post. ROI matters to me. But ROI is not a fixed asset; it's always changing as the inputs change. So I target the overall desired result by choosing inputs accordingly as they present themselves. The cost differential in lubes may or may not outweigh the fuel savings; it just depends.
Going back to quote myself in my first post here:
"I vote for the one that costs the least, because if your conditional statement is true, then why would I use vis as a decision point when cost is likely to have more tangible effect in my life (effect on my ROI)?
You see, you only held wear as a constant, but not other things. If your statement had indicated that both wear and something else were static, then I may have had a different answer. But typically, the savings for fuel (thinner lubes) is outweighed by the savings in lubes, when you find them on sale, rebated, etc. Sure, thinner lubes can save fuel; I agree. But that tiny fractional savings pales when I find a BOGOF sale, or steep rebate. So I choose on cost before vis, as long as the vis provides the required protection. Vis may save some money, but rebates save a larger percentage in overall ROI at times (but not always). Hence, my quote above; I vote for the one that costs the least, because if I assume that wear control is assured, and knowing that vis has little effect on my economy, then lube cost is the greatest variable to manage. However, if I put on BIG miles annually, that would probably invert and make the fuel economy more valuable than lube cost; perhaps vis would take top honors in that situation. But that's just not my operational pattern, so it does not matter.
And then there's the whole topic of cold starts. While we in the lower 48 really don't have a lot to worry about, there are places in MN, WI, Canada that do matter. So, vis would be more important to them that it is to me. But that is exactly my point; they need to manage to a desired result. They need to first pick a lube that successfully supports cold-starts for their area. Sure, vis is the input to that characteristic. But I would not pick a vis and then hope it works; I would define the result desired and then find a vis that supports the effect. If cold starts were the issue, and you could successfully use 0w-30, 0w-20, 5w-20 all in syn formulation, then the differences in grades don't matter (relative to the desired result). So then you pick the product that costs the least IN THAT APPROVED GRADE RANGE. You likely don't need just one grade, but can survive on a range of grades. See my point? For any given defined result, there are often multiple inputs that will suffice. Grade is just a means to an end when you look at it properly.
I guess we're saying similar things, but from different viewpoints. You're on the south rim of the Canyon, and I'm on the north side. We're staring at the same attraction, from different perspectives. No matter; I appreciate the opportunity to debate the matter. I just don't like these hypothetical "what if ..." threads, because there is no sane way to answer unless you state ALL conditions for a specific application. And by the time you do that, the answer should already become self-evident.
