Mixing viscosities doesn't work

[TallPaul]

The viscosity blending calculator is meant for use with base oils, not fully formulated oils that have VIIs added. However, I think it should work well enough. What happens is the base oils mix together to form a new base oil viscosity and then the VIIs from each oil mix together and work off the new base oil viscosity. A 10w30 mixed with a 10w40 is going to end up either a thick 10w30 or a thin 10w40.

If you mix a straight weight with a multigrade you will spread the VIIs from the straight weight over the whole thing. [Edit: Oops, I meant to say the VIIs from the multigrade would mix over the whole thing.] For example, you could mix straight 30 with 10w30 and end up with something like a 15w30 or 20w30. Or you could mix some 10w with some 10w30 and get maybe a 10w20.

I do think it is better to mix closer grades like 10w30 with 10w40 rather than wide apart grades like 5w20 with 20w50

--that just seems to be asking for trouble. Sure would not use it in the winter, but the 10w30 / 10w40 mix is fine for winter if you normally can use a 10wXX in winter.

[ May 12, 2005, 12:58 AM: Message edited by: TallPaul ]

 

[y_p_w]

quote:

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Originally posted by TallPaul:
If you mix a straight weight with a multigrade you will spread the VIIs from the straight weight over the whole thing. For example, you could mix straight 30 with 10w30 and end up with something like a 15w30 or 20w30. Or you could mix some 10w with some 10w30 and get maybe a 10w20.

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There's a large variety in straight weight oils. Pennzoil HD uses Group II base oil with a high viscosity index and sub-freezing pour point. Castrol HD uses Group I base oil with a pour point slightly under freezing. So it all depends on which straight weight oil.

 

[TallPaul]

quote:

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Originally posted by y_p_w:
There's a large variety in straight weight oils. Pennzoil HD uses Group II base oil with a high viscosity index and sub-freezing pour point. Castrol HD uses Group I base oil with a pour point slightly under freezing. So it all depends on which straight weight oil.

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Right. And there is Redline Oil, most of which is multigrade without VIIs and so also could be considered straight weight, I suppose.
It would be hard to know exactly what you got mixing a straight weight with a multigrade.

 

[y_p_w]

quote:

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Originally posted by TallPaul:
And there is Redline Oil, most of which is multigrade without VIIs and so also could be considered straight weight, I suppose.
It would be hard to know exactly what you got mixing a straight weight with a multigrade. [/QB]

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I thought I read a Red Line Oil flyer saying that their "single weight" racing oils were essentially equivalent in viscosity to multiweight oils. As far as I know, single weight oils only have to meet a viscosity requirement at operating temps and by definition don't include VII, although API SM might have additional requirements for any oil.

 

[Gary Allan]

I find myself looking at this issue in the same way we look at UOA

I can't worry about this. If you like an oil, for whatever reason, and the offerings in visc don't suit your needs ..either being too thin or too thick ..you add a quart of the oil that will bias the sump one way or the other. Who cares if it's exactly what you think it's going to be?? If you put a heavier quart in ..it will be at a higher viscosity based on the sensible increment of 1 quart added of the higher weight ..and a reduction of one of the lighter weight quarts.

When I do this, I like to stay within one refiner/blender and the particular product line as well (high mileage with high mileage .HDEO with HDEO..etc).

I don't know too much about additives sinking out ..but I imagine that in some mixing you can have different components competing for the same turf ..so to speak.

I think something like RL trumps most additive packages ..even if used in lower ratios (just an opinion). It appears very aggressive.

 

[TallPaul]

quote:

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Originally posted by y_p_w:
I thought I read a Red Line Oil flyer saying that their "single weight" racing oils were essentially equivalent in viscosity to multiweight oils. As far as I know, single weight oils only have to meet a viscosity requirement at operating temps and by definition don't include VII, although API SM might have additional requirements for any oil.

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What I have heard on this site is that the regular Redline motor oils, except for the 5w40, are without VIIs. A lot of straight weight oils may meet fome multiviscosity criteria, such as some straight 30s may also qualify as 20w30s, but to state that on the bottle would seem pointless.

 

[y_p_w]

quote:

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Originally posted by TallPaul:

quote:

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Originally posted by y_p_w:
I thought I read a Red Line Oil flyer saying that their "single weight" racing oils were essentially equivalent in viscosity to multiweight oils. As far as I know, single weight oils only have to meet a viscosity requirement at operating temps and by definition don't include VII, although API SM might have additional requirements for any oil.

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What I have heard on this site is that the regular Redline motor oils, except for the 5w40, are without VIIs. A lot of straight weight oils may meet fome multiviscosity criteria, such as some straight 30s may also qualify as 20w30s, but to state that on the bottle would seem pointless.

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Red Line actually states that their 30 WT racing oil is equivalent to 10W30. It also has a pout point of -58°F. I don't know why they don't just say they're multiweight, but this is how Red Line markets its racing oils.

http://www.redlineoil.com/products_motoroil.asp?subcatID=15
http://www.redlineoil.com/pdf/9.pdf

 

[LVHospiceRN]

quote:

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Originally posted by blupupher:

quote:

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Originally posted by jtantare:
Why would you mix viscosities in the first place? I've seen all the posts on mixing M1 10w30 and 15w50. Why? Just get the 10w40 and be happy. There so much variety of oil out there on the market. But you are going to do one better than the oil companies in the garage? Who are we kidding here.

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Short answer, the mix gives you different properties than a out of the bottle 10w-40.

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So if this is the "holy grail" or even if its just a bit "better" why dont the oil companies do this? I agree...we are just kidding ourselves...

darrell
sin city

 

[MN Driver]

quote:

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Red Line actually states that their 30 WT racing oil is equivalent to 10W30. It also has a pout point of -58°F. I don't know why they don't just say they're multiweight, but this is how Red Line markets its racing oils.

http://www.redlineoil.com/products_motoroil.asp?subcatID=15
http://www.redlineoil.com/pdf/9.pdf

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That's because it is a straight-weight. A synthetic basestock has a different temperature-viscosity profile. In basic terms, a synthetic oil doesn't thin as much as a dino oil will in cold temperatures.

Another example of that is the Amsoil straight-weight:
http://www.amsoil.com/storefront/acd.aspx

quote:

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Exceeds both 10W-30 multi-grade and SAE 30 straight-grade viscosity requirements. Provides outstanding performance in older and modern diesel engines as well as gasoline engines.

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Also it is important to note that it has a pour point of -36F or -38C.

 

[reyjay1]

quote:

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Originally posted by LVHospiceRN:

quote:

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Originally posted by blupupher:

quote:

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Originally posted by jtantare:
Why would you mix viscosities in the first place? I've seen all the posts on mixing M1 10w30 and 15w50. Why? Just get the 10w40 and be happy. There so much variety of oil out there on the market. But you are going to do one better than the oil companies in the garage? Who are we kidding here.

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Short answer, the mix gives you different properties than a out of the bottle 10w-40.

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So if this is the "holy grail" or even if its just a bit "better" why dont the oil companies do this? I agree...we are just kidding ourselves...

darrell
sin city

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short answer: The oil company is mixing for the masses, while we are mixing for an audience of one.

 

[theguru]

Motul website does not recommend mixing their 300v 5w-40 with the other oils in the 300v range. It does state however that the other oil grades can be mixed together. Obviously some chemical difference in the make-up of this particular oil.