Viscosity breakdown a problem or no?


$100 Site Donor 2021
Apr 28, 2008
Ontario, Canada
Well, what can I say. The first oil analysis is factory fill oil. The next three are from the VW dealer, which claim Castrol Edge 5W-40 on the receipt.
The next fill, I did it myself and got a jug of also Castrol Edge 5W-40 from Walmart. I did a Horizon / Oil Analyzers test on it after 5500 miles:

View attachment 96032

The viscosity, while higher than the Blackstone values, is still on the low side, while at the same time, fuel dilution is not bad. So what does this mean?
Also, this is the first time I got a significant titanium reading. Maybe I got the "fluid titanium" version from Walmart? (I threw away the jug already so can't confirm)

P.S. This test report is wrong in that I only added 0.3 qt make up oil. Though this is the first time my car burned any oil since new. Hmmm....
Since fuel dilution is so low, the primary mechanism of viscosity loss being observed is mechanical shearing of the VII polymers.
Jan 21, 2011
ok, I will get an amsoil analysis then.
My oil temps at the end of my short commute range from 170 to 210. The normal operating temperature is around 220, so I know the oil is not reaching full temperature. Is there a cumulative, permanent degradation in viscosity from having fuel in the oil, or is everything back to normal after just one long drive?
Oil temperature does not always correlate to the engine/coolant temperature. During spirited driving, oil temps tend to spike. But during normal driving, oil temps are typically slightly lower than coolant temps. I'd say oil temps of 200 +/- are considered full temp.


Thread starter
Mar 20, 2022
I have separate gauges for oil and coolant temperature. The coolant temp goes up to 194F within a few minutes and stays there. The oil temp takes at least 15 min of driving to get up to 210+. Normally hovers around 220 average temperature. Up past 230 on hard driving.

I would still kind of like to know:
1) if the oil spends most of its life being diluted by fuel, but then you burn the fuel off right before the oil analysis, has the viscosity still been permanently affected by the fuel?
2) My viscosity measured 11.9, whereas the datasheet for the oil says 14.0. Is this considered "a lot" or can other oils do much better than this? I assume even this value of 11.9 is still "acceptable" from the perspective of the engine.
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