quote:
Originally posted by Patman:
Why would the lab think that fuel in the oil would cause it to thicken up? Fuel is going to thin the oil out.
Intuitively that's what I thought too.
Here's a quote from the Blackstone report:
"One minor problem found was in the mild gas dilution and a resulting higher viscosity." They listed fuel % as "TR" for trace. Insolubles were 0.6% agaist the lab's standard of
The "Ask the expert" at Shell's website came back with this:
"Detergent action from ROTELLA T Synthetic may have cleaned up deposits and hence the oil accumulated solids, thus thickening
the oil. The presence of fuel may also indicate higher than normal blowby, which may also contribute to solid loading of the oil."
And our own DrStressor [member 888] came up with this:
"Both the increased solids showing up in the Blackstone analysis and the viscosity increase can be the result of fuel dilution. While dilution of oil with gasoline should DECREASE the viscosity, longer term exposure to fuel will accelerate oxidation. In the case of synthetic oils [Group III in this case], where the base stock is very oxidation resistant, the particulates usually come from the residue of the fuel itself. So the viscosity of an oil from an engine experiencing fuel dilution typically depends on how the car was driven right before the sample was taken. If the engine was run hard enough to drive off most of the fuel, the viscosity of the oil can show an increase as the result of accumulation of oxidation products [solids]..."
So that's why I now believe that fuel dilution CAN result in higher viscosity.
[ September 02, 2003, 07:37 PM: Message edited by: CJH ]