OVERKILL
$100 Site Donor 2021
And this is exactly why UOA's are an important tool for determining the suitable service life of the lubricant. A quality lab will give you the actual oxidation value as well, so, assuming you have a virgin benchmark, you know how far off the reservation you've gone during your OCI. This, coupled with viscosity and TBN can allow you to fine-tune the safe OCI length. @wwillson did this with his engine and found out the limit; found out where oxidation really started to drive up the visc.The thing about oxidative thickening is that it goes from worsening to very bad quite quickly. Don't know if HPL follows a similar pattern.
But after seeing this chart, as unscientific as it would seem, I tried to gauge any thickening during dipstick checks just in case I had gone too long, especially as this chart suggests that different full synthetics have varying life spans.
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