High Mileage Oil vs Extended Fill Oil

Carlostrece

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I've noticed that you can buy a high mileage oil, or an extended fill oil, but there is no oil that is both HM & EF. At least none that I'm aware of

Why is that? Chemistry? Marketing?
 
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Amsoil also claims SS is extended oci and has better leak protection than high mileage.

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Amsoil also claims SS is extended oci and has better leak protection than high mileage.

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That's very useful info. Thanks

Edited in Later: I looked at datasheets. 5w30 oils at KV100..
Amsoil SS claims 10.3 cSt.
Amsoil HM claims 11.1 cSt

In regard to HM cars...
So with Amsoil SS having that much lower op temp viscosity, is it likely that it really uses/leaks less oil than Amsoil HM? If so, the SS additives much be working miracles.
 
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That's very useful info. Thanks

Edited in Later: I looked at datasheets. 5w30 oils at KV100..
Amsoil SS claims 10.3 cSt.
Amsoil HM claims 11.1 cSt

In regard to HM cars...
So with Amsoil SS having that much lower op temp viscosity, is it likely that it really uses/leaks less oil than Amsoil HM? If so, the SS additives much be working miracles.
Viscosity isn't the only tool for reducing oil consumption or leakage.
 
That's very useful info. Thanks

Edited in Later: I looked at datasheets. 5w30 oils at KV100..
Amsoil SS claims 10.3 cSt.
Amsoil HM claims 11.1 cSt

In regard to HM cars...
So with Amsoil SS having that much lower op temp viscosity, is it likely that it really uses/leaks less oil than Amsoil HM? If so, the SS additives much be working miracles.
My best guess would be the amount of ester, shear stability and low Noack.
 
I believe ester can swell seals.
As yes. The ester is the seal conditioner. I used to know that, but somewhere along the way I forgot that. Thank you for the reminder. You (and others) are a great resource of information.

I like and appreciate an oil with good seal conditioner, but I still want a high (within grade) viscosity at full op temp.
 
As yes. The ester is the seal conditioner. I used to know that, but somewhere along the way I forgot that. Thank you for the reminder. You (and others) are a great resource of information.

I like and appreciate an oil with good seal conditioner, but I still want a high (within grade) viscosity at full op temp.
All oils have some level of seal conditioning in order to meet API standards.
 
All oils have some level of seal conditioning in order to meet API standards.
Agreed, but high mileage oils claim to have extra seal conditioner. Sounds like (at least some) extended OCI oils also claim to have extra seal conditioner.

The oils that are both high mileage and extended OCI in one oil sound really good to me now that I know they exist. I might try one someday.
 
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