I'm not sure if your even talking about the same thing as me. If you grab lets say Mobil 1 AFE, Amsoil Signature and have same exact mileage, engine, climate the signature will retain it's viscosity and far less prone to falling out of grade. I mean where have you been with all the Euro Spec oil discussion? What your asking is like saying why is ESP better than EP.
Here is my Subaru fuel diluting monster. First run was Amsoil SS 0w-20. Second Run was Amsoil OE 0w-20. As you can see Signature has better viscosity even with almost double the mileage and more fuel in it.
Maybe we were talking past each other. I was just trying to say that of all the fine qualities about Amsoil and Euro spec oils—and I'm not disputing it's an excellent oil and Euro specs aren't great—holding up against fuel dilution is not one of them. I just didn't think it was possible since you're just mixing a higher and lower viscosity fluid.
Why would the boutique be any thicker than another oil of the same grade?
I don't follow. Why would you go up a grade if getting a boutique? Seems like you should feel safer with a thinner grade if anything no?
I was never aware of fuel dilution phenomenon when I bought this car used at 21k. So I did a close to 5k run and sampled it thinking it was going to be perfect. So I decided I can do 3k max oil changes with cheaper oils. However I recently switched back to Amsoil products and experimenting with 5w30 and 10w30 Amsoil XL 20k formula see how it does with 5-6k runs.
That will be an interesting experiment. I'm curious to see how the XL does. The OE held its viscosity but only had 2800 miles on it.
Thanks for the data. The fuel dilution is pretty high. I recommend to use cost effective oil and do shorter interval. Probably Supertech, Kirkland, or NAPA oil every 5k miles is better than Whatever Superduper PAO oil at 10k OCI because the fuel dilution will be too high as the miles piled up.
Can you share with us how you came to this conclusion? He shows data showing that with DOUBLE the mileage, the Amsoil held its viscosity well, and with lower mileage the "cost effective oil" fell out of grade. Yet you are recommending that he use cheaper oil and change more frequently. How often do you recommend? Should he cut that interval on the M1 AFE down to 1000 miles and resample??
Except he posted data literally to the exact opposite of what you are claiming here.
I won't argue with that. You are correct. I would categorize his result as "hypothesis generating" and worthy of further study.
In a way that cannot be correct. On its face fuel dilution is simple mixing of a lower viscosity fluid into one with a higher viscosity. Therefore one oil cannot resist that any differently than another.
How do you explain the result of the lower viscosity loss with Amsoil with more fuel dilution and twice the miles compared to M1 AFE then? I'm not trying to agitate here. Earnest question. Higher quality VMs with Amsoil so they hold up better to fuel dilution?
It’s going to dilute the base oil full stop - so I think most OTC lubricants will respond similarly … Wonder about a boutique that used mPAO in place of a typical VM …?
Who knows. I’m not agitating either, but when you put a lower viscosity fluid into one of a higher viscosity, then there’s not much room for error.
