Using the conditions you state (normal OCIs, decent typical ICE example, no obscene temps), then you are actually correct.
The difference you're going to be reading about in both the replies above, and those that will follow mine, is the concept of lab proof versus real world data driven results.
The conceptual difference is that syns are more "capable" in some conditions; better at extreme heat, better at holding vis in really long OCIs, better at uber-cold pumpability, etc. But, those all mean exactly zilch when your conditional limitations are in place. Products which are extremely capable in extreme conditions do not always exhibit their superiority when the conditions are not very challenging. Having "more" of something when it's not required is of no real tangible benefit, despite the nearly hysterical drum-beating cacophony of the masses claiming it to be so.
I've got over 25,000 UOAs in my database by now, and there's actually very good proof that good quality conventional oils do every bit of the job as well as synthetics, under the parameters you state. There is no credible claim to say that syns are "better" under the conditions you operate in. I have personally run home experiments in multiple vehicles over the years and posted the results here. I have studied (literally) tens of thousands of UOAs; I'm a statistical process quality control engineer by trade. I can say without any compunction whatsoever that syns do NOT perform "better" when the use factors are totally "normal". And in fact, I've seen many examples where the capability of dinos far exceeds what most would believe to be true.
Syns are great products and they are worth the expense ONLY when the circumstances of their use allow their capability to shine brighter than a conventional oil. If you cannot differentiate the claimed superiority of a product from those of other choices, then the reality is that the product is not actually "better", despite all the marketing hype and bloviating hypothesis.
Simply put, there's a huge difference between which MIGHT be "better" IF something MIGHT happen, versus something not actually doing any better because the conditions are not challenging enough to bring out disparities between product performance.
Here's a few examples of how this really works in the crankcase of your vehicle: (I am using simple numbers for the sake of the example)
EX 1: ability to hold soot in suspension
Suppose you have an engine that produces 10 grams of soot every 10k miles (1 gram/1k miles). Now you have two oils to choose from ...
oil "A" is capable of holding 30 grams of soot in suspension before the oil add-pack gets overwhelmed and it will leave deposits behind
oil "C" is capable of holding 15 grams of soot in suspension before the oil add-pack gets overwhelmed and it will leave deposits behind
Now, if your planned OCIs are only 5k miles, you're only going to have around 5 grams of soot in the lube, total. That's WELL below both the total capability of the soot carrying capacity of both lubes. Even if you accidentally overrun the planned 5k mile OCI by 3k miles, you're still well below the danger level of both lubes. Was oil A "better" in these circumstances? Well, not really - none whatsoever. Despite the claimed superiority, the conditions will never get so bad that the "better" oil can ever distinguish itself. Only if the OCI went over 15k miles would it really make a difference.
EX 2: ability to tolerate extreme temps
Suppose you drive a normal n/a engine with no known design flaws. The typical operating temp of the oil is kept "normal" by an OEM oil cooling circuit, and the oil typically runs around 210F. Even if you sit in stop/go traffic in summer in your area, it still only gets up to around 220F, because the OEM cooler is using a liquid/liquid cooler circuit to dissipate the heat from the oil into the coolant, and then dump it to atmosphere via the radiator.
oil "A" can survive to 300F before coking and causing deposit issues
oil "C" can survive to 250F before coking and causing deposit issues
The reality is that both oils are more than capable of sustaining even the most extreme temp your situation experiences. That oil A can survive "more" heat is of no consequence, because the conditions never get that extreme. The higher temperature capability of oil A matters not; it's simply wasted capacity. Oil A cannot distinguish itself over oil B because the condition don't get hot enough in real use.
The same can be said of cold temps; if you never get below freezing in your area, then pumpability at -25F is kind of moot; it doesn't happen to you.
The concept to understand above is that until a condition (temps, OCI, contamination, etc) exceeds the capability of the lessor product, then the superior product isn't doing "better", because both are doing "well enough" to survive the operational conditions.
As I'm sure I'm going to be challenged for my proof, I offer these:
Reviewing UOA Data Used oil analyses (UOAs) are tools. And like most tools, they can either be properly used or misused, depending upon the application, the user, the surrounding conditions, etc.= There are already many good articles and publications in existence that tell us how to interpret...
bobistheoilguy.com
Originally Posted By: JLTD Guess I need to run the Amsoil OE I just bought for MUCH longer than 5000 miles! Make it 10k at least....and sample and leave it in. If you do a lot of highway miles.... you might be good for 20k
bobistheoilguy.com
Ran another 10k miles on dino ST in my wife's 1995 Villager. Fe is up a bit, but it's actually only "average" now, as seen in the macro data for 10k miles. In the past, it was below average, but now on par with others. No worries for me; I'll continue to monitor it. Averaging 1.9ppm of Fe per...
bobistheoilguy.com
That something CAN be better, does not automatically mean it WILL be better; that depends upon the circumstances. The reality is that
unless a product can distinguish itself in real-world use, under the conditions which you can reasonably expect to occur, then there's no ability to claim any one product is superior to another. Lab testing (and even field testing) which exhibit uber-stupid-extreme conditions you'll never see really are not "proof" that something is better; it's only proof that marketing and rhetoric are proven ways to separate a fool and his money.
- otherwise, they implode...
