2017 Lexus GS350, 3.5L V6, Factory Fill, 873 miles

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Factory fill that I dumped early from my new GS-350. Happy to see no fuel dilution on this Direct-Injection engine. However, viscosity is pretty low even for a 0W-20. I re-filled with *gasp* Mobil 1 0W-20 Annual Protection.

 
This is Blackstone, so any data on fuel dilution is suspect. With viscosity nearly out-of-grade after 800 miles it seems very likely a fair amount of fuel dilution is present. Notorious diluters like Honda and Hyundai get to 6.0 or 6.2, but only after 5k + miles.
 
Does fuel that makes its way into the oil "evaporate"? I would think gas in oil would tend to evaporate if the oil reaches operating temperature and stays there for awhile.
 
This rather high viscosity drop in merely 873 miles is 'solely' due to shear-thinning of high VII FF oil.
Flash temperature of 420F does not reflect fuel dilution in this GDI engine, IMHO.
One might be seeing clear indications of fuel dilution after say, 8730 miles.
 
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Originally Posted By: btanchors
Does fuel that makes its way into the oil "evaporate"? I would think gas in oil would tend to evaporate if the oil reaches operating temperature and stays there for awhile.


Gasoline is not homogenous but rather has a large number of components, both heavy and light, each of which has their own evaporation point, some of which are quite high. At typical oil operating temperatures, only about half of gasoline that enters the oil will evaporate. So, once gasoline enters the sump, some of it will remain under any circumstance.
 
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