cold flow with oil aging?
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not true, old drivers dont go out in the cold as much as young drivers!
I, too would be interested in seeing such data. I guess a non-scientific test would be using the freezer, keeping a virgin sample, then taking a sample of the used oil and placing them both overnight in the freezer and comparing flow ability.
I have seen UOA of extended drain high end synthetics that thickened out of grade during use. One would only think that the Winter rating number changed proportionately as well, ie a 15w40 ended up 20W-50 after use.
I have seen UOA of extended drain high end synthetics that thickened out of grade during use. One would only think that the Winter rating number changed proportionately as well, ie a 15w40 ended up 20W-50 after use.
Originally Posted By: widman
Anyone know of any studies or papers that show the effects of aging on oil flow in cold temps?
Richard, I've wondered that myself particularly with high VII oil's that tend to shear in service. The shearing affects the 100C vis more than the 40C vis, consiquently the VI declines in service. Using your viscosity/temp graph, the lower VI will result higher projected cold viscosities.
In reality, I don't think the shearing of the polymer thickeners increases the oils viscosity at lower temp's at all.
VII's are one element that really mess with the accuracy of the kinematic viscosity of oil as it relates to actual operational viscosity in an engine.
The non-Neutonian viscosity measures; namely MRV and HTHS, would seem to be better set points between very cold and very hot from which to graph an oil's viscosity. This way you are eliminating the affects of VI and VII's of new and used oils alike.
Anyone know of any studies or papers that show the effects of aging on oil flow in cold temps?
Richard, I've wondered that myself particularly with high VII oil's that tend to shear in service. The shearing affects the 100C vis more than the 40C vis, consiquently the VI declines in service. Using your viscosity/temp graph, the lower VI will result higher projected cold viscosities.
In reality, I don't think the shearing of the polymer thickeners increases the oils viscosity at lower temp's at all.
VII's are one element that really mess with the accuracy of the kinematic viscosity of oil as it relates to actual operational viscosity in an engine.
The non-Neutonian viscosity measures; namely MRV and HTHS, would seem to be better set points between very cold and very hot from which to graph an oil's viscosity. This way you are eliminating the affects of VI and VII's of new and used oils alike.
My question comes from reality.
I investigated an engine that failed when they tried to start it at about 20F. They took off the filter and the oil would not pour out of it. Pulled the pump off and the the oil sat there and took hours to drain out of the turbo. Pulled the plug and it would not drain.
It was a group II 15w40 CI-4 with a -20F pour point. Once the temperature got up into the 30's it drained and began looking normal. Lab came back with an 11.7 cSt at 100C.
Obviously lots of wear metals. Very low soot.
This oil had been used 1300 hours instead of the 250 recommended by Cummins.
I investigated an engine that failed when they tried to start it at about 20F. They took off the filter and the oil would not pour out of it. Pulled the pump off and the the oil sat there and took hours to drain out of the turbo. Pulled the plug and it would not drain.
It was a group II 15w40 CI-4 with a -20F pour point. Once the temperature got up into the 30's it drained and began looking normal. Lab came back with an 11.7 cSt at 100C.
Obviously lots of wear metals. Very low soot.
This oil had been used 1300 hours instead of the 250 recommended by Cummins.
Probabily not the best example since the oil used way past it's normal service life, then you've got the issue of sludge build-up.
I had a somewhat similar experience with an old Renault 21 with an oil leak. I never changed the oil, I didn't care if the engine failed, and just topped up with any used oil that I had.
Eventually the dipstick just show thick black sludge with some lighter oil on top.
I pulled the drain plug and no oil would flow out. I stuck a screwdriver in the drain hole and did manage to get some oil to flow out, maybe 2 litres at most. It was light initially but thickened to a heavy sludge. In total I could only drain two litres out of a 5 litre sump. What remained was thick sludge than wouldn't flow.
I thought you were referring to the affect on the viscosity of normally serviceable oil at colder temps.
I had a somewhat similar experience with an old Renault 21 with an oil leak. I never changed the oil, I didn't care if the engine failed, and just topped up with any used oil that I had.
Eventually the dipstick just show thick black sludge with some lighter oil on top.
I pulled the drain plug and no oil would flow out. I stuck a screwdriver in the drain hole and did manage to get some oil to flow out, maybe 2 litres at most. It was light initially but thickened to a heavy sludge. In total I could only drain two litres out of a 5 litre sump. What remained was thick sludge than wouldn't flow.
I thought you were referring to the affect on the viscosity of normally serviceable oil at colder temps.
The pour point depressants degrade with age . I have read about it in syn oil advertisements but a link to an article no. Have you tried to call Chevron oil? They are helpful.
Not to detract from the point, but I doubt any 15w40 grade oil contains PP depressants.
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