Apparently, oil that is rated @ 5w30 (multi-vis) is in fact 5w oil, that contains an additive which makes it act as if it's 30w when it reaches operating temps. It does'nt "get thicker" as it heats up, it "Acts" thicker when it reaches operating temps. I remember when I went to Harley tech school, There was a seminar by a Valvoline rep, where he explained this in detail. If multi-vis oil got thinner when it got hot, there would be no reason to label it " multi-vis." Straight wheight oils start out at the rated viscosity, and drop from there as the temps climb. Multi-vis oils start @ the lowest rating, and rise to the higher rating when they reach operating temps.

Check this page out.

http://www.blackstone-labs.com/oil_viscosity.html


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