does Amsoil SS thicken with use?

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Jul 22, 2025
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I haven't experienced HPL SC yet but Red Line HP 0W-20 gained 0.4 centistokes after 1,800 miles. HPL Super Car also does that. Does Amsoil Signature Series behave like that too?
I like oils that do that instead of thinning.
Thank you
 
I haven't experienced HPL SC yet but Red Line HP 0W-20 gained 0.4 centistokes after 1,800 miles. HPL Super Car also does that. Does Amsoil Signature Series behave like that too?
I like oils that do that instead of thinning.
Thank you

Was the viscosity tested before use? there's variation in the production, so 0.4 cSt either way is not uncommon. And there's variability in testing. I would consider that the same viscosity after use.
 
All oils will thicken over time due to oxidation. It happens to some quicker than others depending on the formulation. If you can control the oxidation rate you can control how fast it thickens. Amsoil is one of the most oxidation resistant oils on the market.
 
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Everything will eventually thicken with use. But a 0.4 cst change is margin of error since there's a lot of variance in testing. You can test the same sample 10 times and every single one will be a little different.
Another instance of technical decision making on what is likely wholly insignificant data.

Much like "I put oil X in my car and got a .3 MPG improvement!"
 
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