To mix or not to mix...

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blackdiamond

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I have a service appointment scheduled next week for my 2004 Toyota Sequoia so I tried to pick up my normal 7 quarts of Mobil 1 5w-30 Extended Performance and Walmart didn't have any individual quarts so I just brought home the 5 quart jug. I also run 0w-20 in my 2008 Civic and I always have a little extra returned by my mechanic at each oil change that has been collecting in 5 quart jug. I currently have about 2-1/2 quarts that is an unknown mix of 0w-20 and 5w-30. I'm thinking that the economical and smart thing to do is just have him use this excess for the addition 1-2 quarts rather than purchasing two more quarts.

From what I've read on the forum I don't see any reason why it would make much if any difference. The normal OCI is about 10,000 miles and the 5w-30 has been tested to verify that it'll easily go that distance in my application.

Thoughts? At this point I'm planning to just use the oil I have knowing that the final result will be a slightly thinner mix. I know the 0w vs. 5w will only be better and I doubt the 30w will be thinned enough to make a real difference.
 
Have mixed a number of times tending to stick with same brand and various grades - my last winter OCI was maybe a 7w-25
(Who knows) - I tend to get more in line in the hot Summer's getting back to 30 then - but still a mix of 5w, 10w, HM etc ...
Sure can catch more on sale with a little of this stuff ...
 
^ I agree with your assessment.

I would say to use with confidence.. Certainly does not seem to indicate an extreme that could jeopardize that engine.
 
Originally Posted By: blackdiamond
I have a service appointment scheduled next week for my 2004 Toyota Sequoia so I tried to pick up my normal 7 quarts of Mobil 1 5w-30 Extended Performance and Walmart didn't have any individual quarts so I just brought home the 5 quart jug. I also run 0w-20 in my 2008 Civic and I always have a little extra returned by my mechanic at each oil change that has been collecting in 5 quart jug. I currently have about 2-1/2 quarts that is an unknown mix of 0w-20 and 5w-30. I'm thinking that the economical and smart thing to do is just have him use this excess for the addition 1-2 quarts rather than purchasing two more quarts.

From what I've read on the forum I don't see any reason why it would make much if any difference. The normal OCI is about 10,000 miles and the 5w-30 has been tested to verify that it'll easily go that distance in my application.

Thoughts? At this point I'm planning to just use the oil I have knowing that the final result will be a slightly thinner mix. I know the 0w vs. 5w will only be better and I doubt the 30w will be thinned enough to make a real difference.


You will probably end up with a really light 5w-30 IMHO. I am personally not a fan of mixing, but it likely isn't going to hurt anything to run it and it makes economic sense.
 
The winter rating is not worth anything if you start mixing, and the kv could be artifically high. But I doubt it influences the HTHS negatively if you just assume that it's the lowest of the 2 (or 3 etc).

There's no saying what the TBN will do, but the flaspoint will also equal the lowest of theoils you added, and noack the highest.

All that said, look at my signature.... the oil is in there now for 10k miles and due changing end of the month. But all of them are really overkill for my applicaton, and circumstances, and I change at about 60% of the regular oci...
 
All of the oils in play are Mobil 1 EP so I would think that it wouldn't upset the additives too much to mix. I tend to be conservative and wouldn't mix brands or even Mobil 1 with M1 High Mileage with M1 EP. I almost grabbed two quarts of 10w-30. I live in Washington State so the climate is fairly mild so I don't have to worry about the extreme temperatures. Max is under 100 degrees for a rare day and it's rarely below 30 degrees in the winter.
 
I've gone back and fourth on this for years. Ultimately, if the Brands are constantly changing formulations and you keep their stock on hand in quart bottles for instance, you may pick up some from 2013 and some from 2016. They will all say "Pennzoil Platinum" but some will have GTL and the others won't. They even adjust additives from time to time. So i don't see where any mixing is going to give you problems anymore.
 
I've been mixing weights for a little while now and I actually like it. My LS460 takes 9.1 quarts of 5w20, but it was using a little bit of oil so I tried to "thicken it up" a bit by mixing 6 quarts of 5w30 with 3.1 quarts of 5w20 (or 0w20). So far so good...it's Mobil 1 synthetic so it's all the same formula.

I may stick doing this, I've done it the last 2 oil changes with zero issues and the oil consumption has dropped.
 
As long as you don't get too crazy with the mixing I think it's fine. Esp if it's one or two quarts like the scenario you mentioned.

I remember running some Motorcraft syn-blend 5w20 in the 99 Accord F23. Noticed it was down a quart and topped off with some Mobil 5000. Checked it again a month or so later and it was down another quart. Topped off with some Valvoline MaxLife(also changed pcv valve). Never had to top off again with that car.
 
I am planning on changing the oil in the Lincoln this weekend and using up all the mismatched Peak Quarts left over. Some 10w30,10w40,5w20 and 5w30. Just gonna dump all in and go with it. It's soooo Hot here I could run 20w50 in that car.
 
If it's all M1 EP I wouldn't worry about it. I'm going to put a Supertech Synthetic mix in the Mustang. 5 qt of 10W30 + 3 qt of 5W30. I already had the 5W30 and the 10W30 should make it a little more shear stable since it's 10.0 vs 9.4 in Shear Stability.
 
Originally Posted By: Jetronic
The winter rating is not worth anything if you start mixing, and the kv could be artifically high. But I doubt it influences the HTHS negatively if you just assume that it's the lowest of the 2 (or 3 etc).

There's no saying what the TBN will do, but the flaspoint will also equal the lowest of theoils you added, and noack the highest.

All that said, look at my signature.... the oil is in there now for 10k miles and due changing end of the month. But all of them are really overkill for my applicaton, and circumstances, and I change at about 60% of the regular oci...


I'm a little sceptical of some of your assertions. I find it hard to believe if you mix 50% GII+ with 14% NOACK and 50% PAO with a 6% NOACK that you would end up at 14%. In the NOACK Test you would generate the same 14% from the GII+ but the volume would be halved so you would end up closer to 10% for the mixed base stock.

Otherwise most oils would fail the NOACK Test because they would have the same NOACK as the Group I Additive Carrier Fluid.
 
Last edited:
Originally Posted By: Gene K
Originally Posted By: Jetronic
The winter rating is not worth anything if you start mixing, and the kv could be artifically high. But I doubt it influences the HTHS negatively if you just assume that it's the lowest of the 2 (or 3 etc).

There's no saying what the TBN will do, but the flaspoint will also equal the lowest of theoils you added, and noack the highest.

All that said, look at my signature.... the oil is in there now for 10k miles and due changing end of the month. But all of them are really overkill for my applicaton, and circumstances, and I change at about 60% of the regular oci...


I'm a little sceptical of some of your assertions. I find it hard to believe if you mix 50% GII+ with 14% NOACK and 50% PAO with a 6% NOACK that you would end up at 14%. In the NOACK Test you would generate the same 14% from the GII+ but the volume would be halved so you would end up closer to 10% for the mixed base stock.

Otherwise most oils would fail the NOACK Test because they would have the same NOACK as the Group I Additive Carrier Fluid.


I found that in a white paper. The group 1 carrier oil would be in very small amounts then the effect can be minimal, but if you mix larger amounts it apparently isn't linear at all. With only 10% carrier fluid, most of it will have evaporated before the end of the Noack test.

To use your example, you would end up with something like 13% Noack instead of the expected 10% if those things behaved linear. But what it does do, is the Noack % will drop faster over time. but so does the oil level.
 
In BITOG mixology (they call it blending, but that's what oil manufacturers do), everyone expects that additives and the like behave linearly, and cumulatively...i.e. half of this has half of the effect, half of that has half of the effect, and combined, they all add up back to 1.

It doesn't work like that, nothing in these fields is linear in response from 0 to 100%.

So nothing ... BAD ... is likely to happen, unless you are relying on some or another particular aspect of an oil, it's behaviour (especially in cold), or it's actual approvals.
 
Originally Posted By: Jetronic
Originally Posted By: Gene K
Originally Posted By: Jetronic
The winter rating is not worth anything if you start mixing, and the kv could be artifically high. But I doubt it influences the HTHS negatively if you just assume that it's the lowest of the 2 (or 3 etc).

There's no saying what the TBN will do, but the flaspoint will also equal the lowest of theoils you added, and noack the highest.

All that said, look at my signature.... the oil is in there now for 10k miles and due changing end of the month. But all of them are really overkill for my applicaton, and circumstances, and I change at about 60% of the regular oci...


I'm a little sceptical of some of your assertions. I find it hard to believe if you mix 50% GII+ with 14% NOACK and 50% PAO with a 6% NOACK that you would end up at 14%. In the NOACK Test you would generate the same 14% from the GII+ but the volume would be halved so you would end up closer to 10% for the mixed base stock.

Otherwise most oils would fail the NOACK Test because they would have the same NOACK as the Group I Additive Carrier Fluid.


I found that in a white paper. The group 1 carrier oil would be in very small amounts then the effect can be minimal, but if you mix larger amounts it apparently isn't linear at all. With only 10% carrier fluid, most of it will have evaporated before the end of the Noack test.

To use your example, you would end up with something like 13% Noack instead of the expected 10% if those things behaved linear. But what it does do, is the Noack % will drop faster over time. but so does the oil level.


I'm still having a hard time picturing why half as much GII+ would "cook off" nearly twice as much by volume but will concede the effect is nonlinear. It also makes me wonder how it's possible to produce 50% GII+/GIII Blends with 11% NOACK.
 
Originally Posted By: Gene K
Originally Posted By: Jetronic
Originally Posted By: Gene K
Originally Posted By: Jetronic
The winter rating is not worth anything if you start mixing, and the kv could be artifically high. But I doubt it influences the HTHS negatively if you just assume that it's the lowest of the 2 (or 3 etc).

There's no saying what the TBN will do, but the flaspoint will also equal the lowest of theoils you added, and noack the highest.

All that said, look at my signature.... the oil is in there now for 10k miles and due changing end of the month. But all of them are really overkill for my applicaton, and circumstances, and I change at about 60% of the regular oci...


I'm a little sceptical of some of your assertions. I find it hard to believe if you mix 50% GII+ with 14% NOACK and 50% PAO with a 6% NOACK that you would end up at 14%. In the NOACK Test you would generate the same 14% from the GII+ but the volume would be halved so you would end up closer to 10% for the mixed base stock.

Otherwise most oils would fail the NOACK Test because they would have the same NOACK as the Group I Additive Carrier Fluid.


I found that in a white paper. The group 1 carrier oil would be in very small amounts then the effect can be minimal, but if you mix larger amounts it apparently isn't linear at all. With only 10% carrier fluid, most of it will have evaporated before the end of the Noack test.

To use your example, you would end up with something like 13% Noack instead of the expected 10% if those things behaved linear. But what it does do, is the Noack % will drop faster over time. but so does the oil level.


I'm still having a hard time picturing why half as much GII+ would "cook off" nearly twice as much by volume but will concede the effect is nonlinear. It also makes me wonder how it's possible to produce 50% GII+/GIII Blends with 11% NOACK.


the GrpII+ would be the higher viscosity oil of the 2, I think.... GrpIII is very limited in it's viscosity range, only light base oils. And/or the amount of GII+ is exceedingly small?

I looked for the paper or presentation where I got that from, but had no luck so far. Think it might have been by dr Boris Zhmud
 
Last edited:
Originally Posted By: Shannow
In BITOG mixology (they call it blending, but that's what oil manufacturers do), everyone expects that additives and the like behave linearly, and cumulatively...i.e. half of this has half of the effect, half of that has half of the effect, and combined, they all add up back to 1.

It doesn't work like that, nothing in these fields is linear in response from 0 to 100%.

So nothing ... BAD ... is likely to happen, unless you are relying on some or another particular aspect of an oil, it's behaviour (especially in cold), or it's actual approvals.


The only thing it really needs to do is last 10,000 miles because that's my standard OCI for it.
 
I'd do it in heart beat. Just like topping off a few times with what's on the shelves at the store in the out-back. Big deal. It'll love it and you'll have gotten you bottle count under control
laugh.gif
 
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