Synthetic Oil "Groups"

[SHAMUS]

For years I have used and still do, Red Line motor oil. Early on, I heard it was a "Group 5" synthetic oil. What I do not understand is what defines an oil's "group," and wither one is chemically better than another. Yes, I do understand certain properties of an oil, like HTHS, viscosity index, etc, might suggest a better quality for it over another. But for me it comes down to lubricity in all temp ranges, cleanliness, and breakdown resistance. So, can you guys explain to me these groups? (i.e.: I have heard that Mobil 1 is a Group III or IV, and much cheaper than a Group V. WHY?)

 

[Quattro Pete]

Something for starters:
https://www.machinerylubrication.com/Read/29113/base-oil-groups

By the way, no oil is 100% group V, or 100% any other group for that matter.

 

[StevieC]

Group-III's that are highly refined can be considered synthetics now.

Source: https://www.machinerylubrication.com/Read/29113/base-oil-groups

Basestocks while still important are not as important as they used to be thanks to great additives today that allow an oil do a lot more without having to rely on more expensive basestocks, assuming that you are starting with at least a Group-III basestock or better.

 

[oil_film_movies]

Originally Posted by Quattro Pete
Something for starters:
https://www.machinerylubrication.com/Read/29113/base-oil-groups
By the way, no oil is 100% group V, or 100% any other group for that matter.

in the product, 15%-30% of the mass is the additive package. The rest is Base Oil.
Typically we see a mix of groups for sure. Don't forget "Group3+" which is higher quality than Group3 3+ is PurePlus (Pennzoil-Shell) and other oils use it at times too.

One thing is for certain: PAO (Group4) and POE (Group5) are both more expensive than Group3 or Group3+ synthetic base oils, so a formulator wouldn't use the expensive stuff unless a tangible performance benefit is there.
Originally Posted by SHAMUS
(i.e.: I have heard that Mobil 1 is a Group III or IV, and much cheaper than a Group V. )
The MSDS sheets from a lot of different Mobil1 oils have shown that their dexos1 oils, depending on the weight, have a decent percentage of PAO, mixed with Group3. They might have a little ester (Group5), probably not a lot.

Still, it is true that some amazing additive chemicals can make up for the absence of the expensive base oils, Group4 & Group5. To some extent anyway. Current oils only use Group4/5 when they have to in order to meet the specs targeted ....and/or make a racing oil that doesn't embarass the oil company.

For example, M1 Racing Oil is nearly all-PAO, and Redline is targeted at racing & hard driving, using lots of POE for high temperatures.

 

[shanneba]

The bobistheoilguy.com page currently has a good explanation of the different oil "groups" and how the lower groups are refined.

https://www.bobistheoilguy.com/

Summary of Section II:
While Group III base oils have many positive characteristics that approach Group IV and V oils, Groups IV and V are truly synthesized oils using selected starting atoms or molecules, with specific and predictable outcomes.
So hopefully, we have at least clarified the issue somewhat regardless of which side of the issue you may tilt.

 

[bbhero]

Really great post ofm....

 

[MolaKule]

Dupe

 

[OilUzer]

I read somewhere iirc that anything with 0 in it i.e. 0Wx must have a very good base oil but others (5Wx or 10Wx) don't necessarily have to have the best base oil. They could (in premium oils) but they can be made with cheaper (more inferior) base oil! But 0W can't be made with poor/cheap/inferior base oil! ... Is that true?

 

[The_Nuke]

Originally Posted by OilUzer
I read somewhere iirc that anything with 0 in it i.e. 0Wx must have a very good base oil but others (5Wx or 10Wx) don't necessarily have to have the best base oil. They could (in premium oils) but they can be made with cheaper (more inferior) base oil! But 0W can't be made with poor/cheap/inferior base oil! ... Is that true?


Eh, it could be, but there are always caveats it seems.

Best rule of thumb I like to follow is that anything 0w-xx will be a synthetic, and as a general rule synthetics will outperform non-synthetics. Does that mean my car will benefit more from the 0w-xx oil? No, but if it is going to derive a benefit from one oil over another, that is a more likely scenario for it to do so.

Now whether or not I can afford one oil over another is a diff question, and it's usually the one whose answer dictates the choice in oils.

 

[SonofJoe]

It's wholly incorrect to think that a modern PCMO contains 15 to 30% 'additive'.

A wide multigrade oil might contain 10% commercially usable, liquid VII but that translates into just 1% of solid VII 'rubber' & 9% base oil (for handlability).

An oil might typically contain 6% of commercially usable ashless dispersant but this might translate to just 3% of 'neat' ashless plus 3% of base oil (for handlability).

Almost any lubricant additive you can think of will contain some base oil as a carryover from its manufacturing process.

Typically engine oils typically contain at most, 8% 'neat' additive with the remaining 92% consisting of base oil of some description.

 

[CT8]

It is nice to have industry professionals on board to straighten us out

 

[oil_film_movies]

Originally Posted by SonofJoe
Typically engine oils typically contain at most, 8% 'neat' additive with the remaining 92% consisting of base oil of some description.
Yet that's not the way the total oil is constructed. First, a DI package (non-base-oil) is selected that has a chance of meeting a targeted spec. Then VII can be added to adjust viscosity, and finally the last ~80% of the total oil is base oil.
What you're saying is technically correct thoug, as the DI package you buy from Afton or Lubrizol (examples) has oil in it as well as all the wicked chemicals.
And I wonder how often the DI package has Group2 in it for an oil that is labelled "100% synthetic"! Of course, that doesn't amount to much anyway, so if all the rest is PAO, we can say its 100% PAO without getting anal about it.

 

[BrocLuno]

I think I'll take Joe's word on this ...

 

[oil_film_movies]

Originally Posted by BrocLuno
I think I'll take Joe's word on this ...

As I said above, SonOfJoe is technically correct. Base oil is considered exclusive of the additive package when discussing different oils in the real world, so it is trivial to consider a few percent in the DI package and obsess over that.