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Message: [QUOTE="bismic, post: 1526382, member: 1537"] I have plenty of data with my 5W40 still in the 40 wt range of viscosity (although right at the edge) after 5k miles. Even after 7.5k miles my Delvac 1 ESP 5W40 just barely drops into the high range of the 30 wt specs. My UOA is great. I have never had any fuel dilution of the oil, NOR have I had any detectable moisture content. I am at 210k with original injectors. I have been running the SRL+ tune for over 100k miles. I have been running 7-7.5k OCI's for the last 70k miles. Even if the oil drops to a 30 wt viscosity, then so what? Just like the 5W40 results, there are numerous 6.0L UOA's posted (with great results) when using 10W30. btw - even the 10W30 shears ..... just a little less than a 5W40 due to needing less VII additives in the formulation. Basically any multi-viscosity oil will shear in an engine with a high pressure oil pump and oil actuated injectors. I am definitely not the lone ranger on this, lol. 6.0L UOA's have been posted for a lot of years and lots of (heated) discussions have taken place on this topic!!! [/QUOTE]

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