mixing oils can eat your engine?

[buster]

30+ year chemical engineer and tribologist who's entire career has been nothing but automotive oil says:

"if you mix oils, mix oils of the same brand as some additives between the companies are incompatible"


Unfortunately I've ruined the excitement for those that have fun playing backyard chemist. I get it. You don't want to hear somthing that challenges your belief about mixing oils.


Here is what we know:
1. Different oils use different additive packages to meet specific specifications.
2. Some oils use similar additive systems due to the fact that there are only about 4 major suppliers.
3.There is such a thing called additive clash and detergent competition in which oils of different chemical makeups don't intereact as well as they would by themselves.

So all CATERHAM etc are doing is creating uknowns. You're taking a brand that has a given performance and diluting it and basing the rsesults off of a $25 used oil analysis. No offense but that is extremely naive.

So I have to disagree with you all and I stand by what I said because the information I have received comes from formulators, not internet experts.

 

[buster]

More proof:

Quote:
Can we mix oils?
If we add additives we improve the quality?
It is dangerous to mix engine oils, if they come in different brands, but is essential to respect the performance classes recommended by the manufacturer in the technical book. Especially for synthetic and semi-synthetic lubricants obtained by modern techniques may be blended without damaging the engine. If you mix oils of different viscosity, it can happen that the final viscosity to change, but not essential.

However, if oil is mixed with different performance specifications, the mixture corresponds only to the lower specification of the two!

It's a fatal error when it "improves" with additives already oil additives. As I stated in previous paragraphs, oils and additives increases the performance of oil producers additive own special recipes. If you choose to make a new additive personally do not only deal with composition and the quality further


With that said, I think you are all wrong.

 

[Trav]

Originally Posted By: buster
30+ year chemical engineer and tribologist who's entire career has been nothing but automotive oil says:

"if you mix oils, mix oils of the same brand as some additives between the companies are incompatible"


Unfortunately I've ruined the excitement for those that have fun playing backyard chemist. I get it. You don't want to hear somthing that challenges your belief about mixing oils.


Here is what we know:
1. Different oils use different additive packages to meet specific specifications.
2. Some oils use similar additive systems due to the fact that there are only about 4 major suppliers.
3.There is such a thing called additive clash and detergent competition in which oils of different chemical makeups don't intereact as well as they would by themselves.

So all CATERHAM etc are doing is creating uknowns. You're taking a brand that has a given performance and diluting it and basing the rsesults off of a $25 used oil analysis. No offense but that is extremely naive.

So I have to disagree with you all and I stand by what I said because the information I have received comes from formulators, not internet experts.

Good point Buster. Maybe i don't understand all this about VI and VII as well as some experts here but i look at this way.
If Shell for example spends 18-19 billion dollars on development cost for GTL and years of research i think its safe to assume they have a pretty good idea what they are doing.
They claim the oils made with this base stock are their best top shelf products but someone here on BITOG pops off with PP is better only because it has a higher VI even though it is made from inferior (in comparison) base stocks with maybe a little GTL in the mix.

Now honestly this doesn't add up in my mind. They spend all these resources to develop this product only to skimp on the end product by making it inferior to their next tier product?
Anyone have a bridge to sell me, a long one over the Hudson river might be nice.

http://www.shell.com/global/aboutshell/major-projects-2/pearl/overview.html

 

[buster]

^+1 I agree. I think that makes the most sense. And who's to say the PP VI is the same type as the one used in PU? What if they don't work as good together as they would alone?

Run one of these OEM 0w20's with a VI of 216 through the SEQIIIG test and tell me how great it does.

 

[OVERKILL]

Originally Posted By: S65AMG

I would also point out again that Mobil believe that a higher VI leads to lower wear.

I think that is possibly more important than a drop from an incredible 8.8% NOACK to a sensational 6.6% NOACK.


OK, let's try this again. I'm not arguing that having a higher VI is a negative trait, or even one that isn't desirable. I think it is certainly a trait that you want in a lubricant, and my point I made in the post you replied to and appeared to skim over the part about the natural VI of the base oils supports this theory!

With respect to NOACK and what the OEM's subscribe to with respect to what attributes hold the most weight? Well, it appears Ferrari may hold shear stability and volatility in higher regard than relative VI (as per their choice to use Pennzoil Ultra 5w-40).

And the list of certs/approvals between the two oils I've mentioned several times are almost identical. The difference is that Mobil 1 0w-40 has the GT-R spec, and Pennzoil Ultra 5w-40 has the Ferrari spec.

 

[OVERKILL]

Originally Posted By: CATERHAM

I think you're one of the few that truly understands that a VI as high as technically possible without incurring a lot of trade- offs is indeed the lubrication holy grail of any automotive oil that operates under varying temp's. Viscosity is the most important attribute of an oil but it is of course it is not the only aspect.


But that's exactly my point

A balanced lubricant like Mobil 1 0w-40 with its relatively high VI is balanced for that very reason. XOM could have shot for a "stratospheric" VI but I assume they didn't because it would have compromised some other aspect of the product. Perhaps volatility for example (we know the ultra high VI oils have rather poor NOACK) which we also know is a criteria used by many of the OEM's, as they have a NOACK cap as part of their testing protocol (like Mercedes).

Ergo, there is no "holy grail" in terms of a single trait. The holy grail would be, IMHO, the oil that is the best at everything inside a given suite of design criteria. The lowest volatility, highest VI, best anti-wear performance, best extreme low and high temp performance.....etc. At this point in time I would dare argue that this oil is Mobil 1 0w-40.

I think the disconnect here is that I'm putting emphasis on traits other than VI as having weighted significance as to the ultimate performance of the final product. I see examples of that in the OEM testing criteria where things like NOACK have limits placed on them, obviously making their role in the final lubricant relevant in order to achieve an OEM approval.

 

[OVERKILL]

Originally Posted By: Garak


Nonetheless, since the internal combustion engine was introduced, there has been one unflinching trend with respect to motor oil. It's not anything about thin or thick, or CAFE playing with thin grades, or the Europeans looking for thick grades. It's that VI has increased steadily, and that's been the pattern in North America/Japan and Europe.

Whether it's been to make a motor vehicle useful in severe winter conditions, to improve fuel economy for CAFE, to simplify maintenance through one grade over the year (Europe and here), all of this has been made possible by increasing VI. Of course, car magazines and the automotive histories we read never call it that. They talk about multigrades. They talk about the introduction of synthetics. They talk about how synthetics are great for very high and very low temperature applications. They talk about how oils can save [even small] amounts of fuel.

Really, they're all talking about viscosity index, whether they know it or not. No, I'm not going to go out looking for an oil with a 200+ VI. But, I know which way the wind is blowing, and it's been blowing that way since long before any of us here were driving.


This is very true! (and very well stated!

)But this is also the case because the base oils themselves have improved and have much higher natural VI's than those that they've replaced. This allows the formulation of products like Mobil 1 0w-40 which would previously have required a great deal of polymer to achieve its viscosity curve, and I would argue, would have negatively affected the performance of the product and not allowed it to obtain the certs/approvals that it carries. You don't get a product with a visc curve like it has and a NOACK of 8.8% by loading it full of plastic

 

[buster]

Quote:
Ergo, there is no "holy grail" in terms of a single trait. The holy grail would be, IMHO, the oil that is the best at everything inside a given suite of design criteria.


Exactly.

 

[danthaman1980]

Originally Posted By: Garak
Originally Posted By: danthaman1980
I'll be the first to admit that a poorly thought-out mix could do more harm than good (I wouldn't mix a Group V base with a Group II base, nor an API SG with API SN, nor a 0W-20 with a 10W-60). But mixing similar oils to get something in between is nothing to be afraid of.

That's the thing. Unless I were to be fairly certain the mix I would be coming up with would be more advantageous to me than anything off the shelf, I'd be hesitant.

I'd be more likely to explore at the margins of what's actually available on the shelf. Like you said, if your experience tells you that the average API/ILSAC xw-30 is a little too thin for what you want, and the average 40 grade is too thick, instead of mixing, I'd be looking at something like GC, a multigrade HDEO in a 30 range, possible a High Mileage oil or Defy, or a light 40 (like Mobil 1 0w-40). But, that's just me trusting the oil companies to know more about it than I do.

Now we need to make the world's first open source oil. It will be the mixers' delight.

Garak, all those things I have done already... GC runs wonderfully in the 5.3 when up to temp (that's whats in there right now), and I think it probably has the optimum viscosity characteristics for this engine... the only minor drawbacks are the cost, and my engine seems to like a little bit of Moly which GC lacks. Rotella T5 10w30 runs fine but cold starts in the winter would indeed be problematic. Mobil 1 0W-40 made the engine purr like a kitten but reduced fuel economy quite noticeably. Defy is an interesting oil, I might try it one day. The 5.3 seems to really like Pennzoil Ultra and PP (PP ever so slightly less for some reason), but they could be just a tad thicker. I did run two OCIs with Amsoil XL a long time ago, and it was really nice - but it's to dang expensive.

Really I want a slightly thicker Pennzoil Ultra xW-30 or a slightly thinner Mobil 1 0W-40 - and I'm downright tempted to mix 4 quarts of Pennzoil Ultra 5w30 with 2 quarts Mobil 1 0W-40 at my next oil change.

I admit I'm splitting hairs here - I've only found a few (API SM) oils that I genuinely didn't like, and disregarding those, I could probably get another 200k miles out of this engine on any off the shelf API SN/SM/SL, but my cursed perfectionism won't die.

 

[Garak]

Originally Posted By: Trav
Maybe i don't understand all this about VI and VII as well as some experts here but i look at this way.
If Shell for example spends 18-19 billion dollars on development cost for GTL and years of research i think its safe to assume they have a pretty good idea what they are doing.

Maybe we're all being naive, but I hold out some pretty high hopes for new base stocks like Shell's GTL. VI will continue to improve, and I suspect that in the end, the evolution of GTL will actually assist that. There's nothing wrong with a very low NOACK and shear stability (not to mention cost advantages) as a starting point for a great lube!

Originally Posted By: OVERKILL
This allows the formulation of products like Mobil 1 0w-40 which would previously have required a great deal of polymer to achieve its viscosity curve, and I would argue, would have negatively affected the performance of the product and not allowed it to obtain the certs/approvals that it carries.

Yep, it's that evolution in the products. If something like Mobil 1 didn't have better numbers in all kinds of areas, of course, there might never have been a switch from 15w40 summer and 10w30 or 5w30 winter fills in Europe. Besides, we've all seen how bad some of the old style VIIs were. There's a reason GM was against use of 10w-40 in their engines for a number of years.

Originally Posted By: danthaman1980
Really I want a slightly thicker Pennzoil Ultra xW-30 or a slightly thinner Mobil 1 0W-40 - and I'm downright tempted to mix 4 quarts of Pennzoil Ultra 5w30 with 2 quarts Mobil 1 0W-40 at my next oil change.

You know the rule here (at least if you're not mixing). If attempts with Mobil 1 0w-40, GC, SN/GF-5 PCMO, and an HDEO don't satisfy you, it's time to try MaxLife.

Defy, which you mentioned, is also an acceptable alternative.

 

[Tempest]

Originally Posted By: S65AMG
So the benefit will only accrue from the part of the VI that is provided by the base oil? Any VI increase that comes from polymer has no benefit?

If there was no benefit, why would they boost the VI?


Viscosity of oil running through a viscometer on a bench, and viscosity of oil being squished between two metal parts under load are two different things. A high "on paper" VI can be achieved using a light oil with lots of VII but how well will it protect under real conditions? VII does not provide the same film cohesion as oil.

This is the distinction that must be made.


Originally Posted By: S65AMG

I think it's notable that Mobil see fit to increase their VI further than the base oil alone. They did this even before the modifier was as shear stable as it is now. And this oil is chosen by AMG and also by Nissan for the GTR.

Again, even when they didn't have as stable a modifier, Mobil, AMG, Nissan, favored the oil with the highest VI.

A high VI oil will allow operation under wider temperature conditions. This is a benefit to the OEM. Start up is about "static" viscosity where a high VI applies, and not "dynamic" viscosity in an operating engine.

This is why I think "on paper" VI should be used as a reference only and not as a hard number, especially if it is "calculated" and not actually measured.

 

[danthaman1980]

Originally Posted By: Garak
You know the rule here (at least if you're not mixing). If attempts with Mobil 1 0w-40, GC, SN/GF-5 PCMO, and an HDEO don't satisfy you, it's time to try MaxLife.

Defy, which you mentioned, is also an acceptable alternative.


Why would I need a high mileage oil? My 5.3 is just barely past 205,000 miles ; )

Realistically though, If/when I ever exhaust my stash of PP, PU and GC, I will be giving Defy a try.

 

[CATERHAM]

Originally Posted By: Tempest
Originally Posted By: S65AMG
So the benefit will only accrue from the part of the VI that is provided by the base oil? Any VI increase that comes from polymer has no benefit?

If there was no benefit, why would they boost the VI?


Viscosity of oil running through a viscometer on a bench, and viscosity of oil being squished between two metal parts under load are two different things. A high "on paper" VI can be achieved using a light oil with lots of VII but how well will it protect under real conditions? VII does not provide the same film cohesion as oil.

This is the distinction that must be made.


Originally Posted By: S65AMG

I think it's notable that Mobil see fit to increase their VI further than the base oil alone. They did this even before the modifier was as shear stable as it is now. And this oil is chosen by AMG and also by Nissan for the GTR.

Again, even when they didn't have as stable a modifier, Mobil, AMG, Nissan, favored the oil with the highest VI.

A high VI oil will allow operation under wider temperature conditions. This is a benefit to the OEM. Start up is about "static" viscosity where a high VI applies, and not "dynamic" viscosity in an operating engine.

This is why I think "on paper" VI should be used as a reference only and not as a hard number, especially if it is "calculated" and not actually measured.

There are two viscosity spec's that will allow one to predict the operational viscosity of an oil in an engine at normal operating temp's and higher. That's firstly the HTHSV rating of the oil and secondly the oil's viscosity index.
If two oils have the same HTHSV but different VIs, the oil with the higher VI will be both progressively lighter at temp's below 150C and progressively heavier at temp's above 150C.
Consequently a higher VI oil will be both lighter on start-up while also providing greater high temperature protection in the parts of the engine that can see localized very high oil temp's well in excess of 150C.

That said, an oil's VI is only as good as what's retained in service. The latest crop of high VI 0W-XX oils are as shear stable as there lower VI counterparts. There still are some higher VI oils out there that are not that shear stable, some GP III 5W-50s come to mind, but for the most part oil shear is not a problem, and certainly not with the very high VI OEM oils.

 

[buster]

From a 2003 Subaru Forester owner's manual in reference to MTF:

"Each oil manufacture has it's own base oils and additives. Never use different brands together."

 

[CATERHAM]

Originally Posted By: buster
From a 2003 Subaru Forester owner's manual in reference to MTF:

"Each oil manufacture has it's own base oils and additives. Never use different brands together."

How long did it take for you to dig that up?
Prove positive of a confirmation bias.

 

[buster]

^ Not long at all, it's in my new used car manual.

When will you admit you're not a formulator and are wrong on this issue?

 

[buster]

It amazes me that after speaking to several formualtors and chemists, who said it's not really ideal to mix, you continue to give people fasle information based on what you "believe" to be true. We'll just have to agree to disagree. Compatible, yes. Ideal? No.

 

[CATERHAM]

Originally Posted By: buster
^ Not long at all, it's in my new used car manual.

When will you admit you're not a formulator and are wrong on this issue?

I'm not a formulator since I only blend fully formulated oils that the formulators themselves say can be blended.

When are you going to admit you have an unscientific confirmation bias?

 

[buster]

haaa funny, uncientific is taking two brands of oils, with differen chemistry and claiming it's better. Doesn't get much more scientific than that.

 

[buster]

Think about what you just said. I'm taking the advice of SCIENTISTS, and you are claiming to know more than they do and are saying I have an unscientific confirmation bias. Too funny.