Oil Viscosity Question
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From: Isanti, MN
Drive your truck, it'll be just fine.
Super Moderator
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From: Isanti, MN
That's not true, they mix together and form a thicker oil. There's nothing wrong with extended drain intervals with this either.
Cargo Master
Joined: Sep 2012
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From: Laramie, WY
That's right...they blend together to make a slightly thicker oil. They won't stay seperate and it won't cause any trouble.
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I do not see how two different engineered viscosity oils will mix as this is at the molecular level not fluid . As the heat increases the individual molecule oils will attain their own viscosity. There was always a warning from experts that mixing same viscosity oils was ok ,but not different viscosities.
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From: Sioux Falls Area
so he will have 14% of his oil reaching a different viscosity at a different rate than the other 86%.
the 14% will be homogenously distributed amongst the other 86%.
whether they mix at a molecular level or not, they are mixed at a fluid level and will act as a homogenous fluid.
do you suppose that all 6 quarts of 5w20 were EXACTLY 5w20? i would be they aren't.
the 14% will be homogenously distributed amongst the other 86%.
whether they mix at a molecular level or not, they are mixed at a fluid level and will act as a homogenous fluid.
do you suppose that all 6 quarts of 5w20 were EXACTLY 5w20? i would be they aren't.
More Turbo
Joined: Feb 2003
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From: Grand Rapids, MI
Other than the normal awareness for unusual noises I would not even think twice about it. Might not add the 0w40 intentionally but having done so I highly doubt it will make any issues, especially a nice synthetic like M1 and especially in a high VII multi weight like 0w40 (0 base weight with VII to bring it up to a 40 weight at operating temp).
Cargo Master
Joined: Sep 2012
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From: Laramie, WY
You can make your own custom viscosity by mixing the proper amounts of two differnt viscosity oils. This is rarely necessary due to the wide range of oil available.
The viscosity of a given oil is changed with polymeric additives. These are long chain molecules that help to increase the viscosity of a base oil. The problem they present is that they can be broken down under high shear conditions.
I'll also note that I am not an expert in tribology. But if you want to get a great book I recommend:
Engineering Tribology 4th Edition
ISBN: 978-0-12-397047-3
I'm only part way through that book. It was purchased because the compnany I work for has a turbine needing an oil change due to a high total acid number (TAN). We have been unable to treat the oil to reduce it and now I understand why. The cost of the oil change is somehwere around $40K so the cost of the book was negligible.
The viscosity of a given oil is changed with polymeric additives. These are long chain molecules that help to increase the viscosity of a base oil. The problem they present is that they can be broken down under high shear conditions.
I'll also note that I am not an expert in tribology. But if you want to get a great book I recommend:
Engineering Tribology 4th Edition
ISBN: 978-0-12-397047-3
I'm only part way through that book. It was purchased because the compnany I work for has a turbine needing an oil change due to a high total acid number (TAN). We have been unable to treat the oil to reduce it and now I understand why. The cost of the oil change is somehwere around $40K so the cost of the book was negligible.
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