Why isn't High Mileage oil the "standard" oil?

If it has no ill effect, then why not?
I guess this is my question. Would more "seal conditioners" make seals "swell" more? If so, I don't want a functioning seal to swell more.

Unless your saying the seal only absorbs so much anyway, in which case were back to HM oil doesn't help.

🤷‍♂️ Whats a non-chemist to do around here. Perpetually lost.
 
There isn't necessarily some "seal conditioning" additive in the oil. The seal conditioning/swelling that prevents leaks is coming from the group 5 base oils (esters, AN, etc) inherent seal swelling properties, which are blended into oils to varying degrees to counter the PAO inherent seal shrinking effects. Group 1-3, and especially group 4 (PAO) tend to shrink seals and make them more brittle over time. So conventional (group1-3) and "synthetic blend" (group 1-3/4) oils will not protect seals to the same degree as a group 4/5 full synthetic oil. The Amsoil SS is a good example of a group 4/5 full synthetic oil with a good dose of ester. "High mileage" is a marketing term for added ester/AN because the average person buying oil has no idea what esters/AN or oil groups mean and how they affect their engine.
So in the case of a semi syn "HM" oil like Havoline 10W-30 - are you saying they add Group 4/5 to some Group 1/2 - likely? Or is there more to it?
https://www.chevronlubricants.com/en_us/home/products/havoline-high-mileage-synblend-motor-oil.html
 
In marketing, there's a stigma of using "high mileage" in a new car and then there's a preference for some who want a "medicine" when their cars are older and not feeling as nice as they used to. You can't sell assist living to young teenage who wants to look sporty is the example I would use.
 
I guess this is my question. Would more "seal conditioners" make seals "swell" more? If so, I don't want a functioning seal to swell more.

Unless your saying the seal only absorbs so much anyway, in which case were back to HM oil doesn't help.

🤷‍♂️ Whats a non-chemist to do around here. Perpetually lost.
I've already read here, for better or worse, that the esters or "conditioners" can only "swell" a seal so much. That a seal won't just keep ballooning outward indefinitely, and that that's why it's safe to use HM oils even when the vehicle is brand-new, that it basically just wouldn't have an effect in that case.
 
Just a high level question and response since we don't want anyone having to write a book for us.

What are seal compatibility test requirements and how is it tested?
Also how many different seal materials are out there (e.g. fancy cars vs. what I drive) and to what extend or % are the seal materials the same?

To meet for example API SP, is it just on paper that it (seal compatibility) was taken into consideration and based on xyz chemical reactions, this oil is compatible with majority of seals ...
Or a real test running in an engine and/or abusing the seal for 5,10,20,50K miles? Or experience gained over decades with the material so it can be rubber-stamped?

Another Q:
As an example, iirc one of Audi tests (Part of A40?) require a track test which is a rigorous test that some others may not conduct or at least not to that extreme. Are there other more extensive seal compatibility tests relative to SP for example?
 
You don't need the extra seal conditioner in a newer lower miles engine. So why pay for it?

Furthermore, many experts online say you don't want extra seal conditioner in a newer engine because (they say) it would swell the new seals causing them to wear faster. That makes sense to me, but others may disagree.

So bottom line IMO is HM oil isn't needed for a newer car and might be detrimental for a newer car's seals.
 
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Mobil1 HM oil vs Pennzoil HM Platinum. The Mobil 1 HM oil did not stop the leaks in my daughters 2005 Honda Civic, but the Pennzoil HM did. No leaking on the card board. Both oil tested for 2 oil changes (5,000 mile dumps) and Mobil1 was first up and never sealed the engine. The Pennzoil stop dripping oil on the cardboard midway though the first oil change. That became it's oil choice till the head gasket gave up the ghost.
 
I've already read here, for better or worse, that the esters or "conditioners" can only "swell" a seal so much. That a seal won't just keep ballooning outward indefinitely
But there is the circular argument.

Synthetics already have seal conditioners.

HM has more seal conditioner, so there better.

But you can only "swell" the seal so much? So which is it - more is better, or enough is all you need?
 
But there is the circular argument.

Synthetics already have seal conditioners.

HM has more seal conditioner, so there better.

But you can only "swell" the seal so much? So which is it - more is better, or enough
Basically the point of my question is, do "extra seal conditioners" create any drawbacks, the way that every oil formulation is a balancing act.

As far as whether or not more is better or enough, that depends on the engine. In an older engine with tired seals, I would think you would want more. But since seals will only "swell" to a certain point, I would think that "more" in a newer engine just wouldn't make any difference at all.
 
Basically the point of my question is, do "extra seal conditioners" create any drawbacks, the way that every oil formulation is a balancing act.

As far as whether or not more is better or enough, that depends on the engine. In an older engine with tired seals, I would think you would want more. But since seals will only "swell" to a certain point, I would think that "more" in a newer engine just wouldn't make any difference at all.
I am just as lost as you, but I don't think I want my new seals to swell much at all - would just cause them to wear out faster.

Shaft seals are designed to wear and still seal. It relies on spring pressure and the curvature of the seal lip and flexibility of the material to deal with the wear. If you over-swell the seal early on your simply wearing it out early - assuming this is in fact how these "conditioners" work.

On old industrial shafts you would use a rope seal in a metal casing, and when it started to leak you would tighten it some more, until eventually tightening it didn't help and you had to replace it. If you over tightened it at some point it would simply wear out sooner. Auto seals use a spring to do exactly this, so if there too tight to start they last less time. Reason I don't use HM oils. I have no interest in "over tightening" my seals. However all this is based on my assumption of how seal conditioners work, which no one wants to seemingly confirm or deny?
 
it is all marketing. You are virtuous in buying "high mileage oil" for your precious older engine. If you don't buy high mileage oil you are an abuser.
 
There isn't necessarily some "seal conditioning" additive in the oil. The seal conditioning/swelling that prevents leaks is coming from the group 5 base oils (esters, AN, etc) inherent seal swelling properties, which are blended into oils to varying degrees to counter the PAO inherent seal shrinking effects. Group 1-3, and especially group 4 (PAO) tend to shrink seals and make them more brittle over time. So conventional (group1-3) and "synthetic blend" (group 1-3/4) oils will not protect seals to the same degree as a group 4/5 full synthetic oil. The Amsoil SS is a good example of a group 4/5 full synthetic oil with a good dose of ester. "High mileage" is a marketing term for added ester/AN because the average person buying oil has no idea what esters/AN or oil groups mean and how they affect their engine.
Due to this, do you think a non-HM oil with ester content, such as the 0W grades of Mobil 1 ESP, would be basically as effective at "swelling" older seals as a typical non-Euro spec high mileage oil?
 
Marketing aside, sounds like there have always been seal shrinkage issues or challenges due to aging and/or interaction with oil, etc.

So when it comes to seals:
  • Group 1-3 shrinks a little.
  • Group 4 shrinks a little more.
  • Group 5 swells seals a little but not harmful.
So grp 4 is the real bad boy!

At least that is the summary of my understanding. If not correct, please feel free to explain.

Q:
Historically, when did we realize that we have seal shrinkage problems that are oil related? Did group 4 usage raise that awareness by making things much worse? Or were we used to the problem but group 4 was the last straw? And we needed a solution besides not using group 4?

Now how did the group 5 as the "seal savior" came into play? Was it an accidental side benefit of utilizing grp v?
 
Q:
Historically, when did we realize that we have seal shrinkage problems that are oil related? Did group 4 usage raise that awareness by making things much worse? Or were we used to the problem but group 4 was the last straw? And we needed a solution besides not using group 4?

Now how did the group 5 as the "seal savior" came into play? Was it an accidental side benefit of utilizing grp v?
I believe it was discovered after the the first introduction of PAO Mobil1 in the early seventies. I also believe that's when Mobil1 introduced the addition of ester into the formulation.

I also believe there are no "seal swellers" in oil formulations. Seals don't shrink. They are a rubber compound, some are not, that dries up and crack. ALL oils contain seal "conditioners" and it's part of their certification.
 
Marketing aside, sounds like there have always been seal shrinkage issues or challenges due to aging and/or interaction with oil, etc.
To ensure this doesn't happen, all oils that are API and ACEA approved have to pass seal compatibility testing, regardless of their base oil blend. If the blender uses PAO, its seal shrink tendency is balanced out with something else to counteract that, like esters or AN's.
 
I see. So HM oils must absolutely have ester and maybe even some PAO is a myth! I mean some may but there is no guarantee!
 
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