Link or Information.. WTH is Group III/IV and PAO?

[kartracer55]

I have been reading on here quite a bit lately and the more experienced users toss around these different terms regarding what grouop of base stock an oil is from and all these other things, is there a thread or link that clearly lays this stuff out? I would have a much easier time comprehending on here if I knew, more precisely, what all of these things were. Im sure Im not the only one. Either a link to a thread or somebody's detailed description of the terms would be excellent, Im here for information.

thanks
Jim

 

[cosynthetics]

I'm not extremely articulate so this is from wikipedia....

* Hydrocracked/Hydroisomerized = API Group III base oils. Chevron, Shell, and other petrochemical companies developed processes involving catalytic conversion of feed stocks under pressure in the presence of hydrogen into high quality mineral lubricating oil. In 2005 production of GTL (Gas-to-liquid) Group III base stocks began. The best of these perform much like polyalphaolefin. Group III base stocks are considered synthetic motor oil in North America.[2]
* Polyalphaolefin (PAO) = American Petroleum Institute (API) Group IV base oil
* Synthetic esters, etc = API Group V base oils (non-PAO synthetics, including diesters, polyolesters, alklylated napthlenes, alkyklated benzenes, etc.)


Basically, group III is what is called a hydrocracked oil. It is a dinosaur based oil that has been altered and is allowed to be called synthetic.

Group IV and V are 'true' synthetics.

 

[MGregoir]

Group I is solvent extracted from crude oil. It's a mixed bag of hydrocarbons and in North America has fallen out of favor due to not being of very high quality compared to readily available base stocks that are improvements on it.

Group II is hydrocracked and dewaxed oil to produce more of the desired properties and it reduces unsaturated hydrocarbons, which reduces the tendency of the oil to oxidize and thicken out of grade. Most conventional oils in North America are made up of this.

Group II+ is an oil that would typically have very few unsaturated hydrocarbons and lower wax content. It may not be as fully processed as group III, but it is ahead of Group II for quality. Certain higher quality conventional oils use a higher proportion of this.

Group III is a heavily hydrocracked mineral oil. Most synthetic oils on the market are made up of this. The oil molecules are broken down through a variety of processes until they are much more like what has good lubricating properties, and removes or breaks down molecules with negative performance effects such as waxes. Pennzoil Platinum is the highest regarded group III oil on this site.

Group III+ is the extreme end of this, where the final product is basically nothing like any of the components that went into it, but it is still derived by heavily processing crude oil. An example of this would be Shell XHVI base oils. As well, oils are being developed on gas-to-liquids basestocks which would also produce extremely high quality group III bases, fundamentally synthesized but not falling into the definitions of group IV or V.

Group IV is PAO, which most consider along with group V to be a "true" synthetic. It is made up of base oils made from other hydrocarbons (often derived from natural gas) and is made specifically to be a lubricant, and does not have origin as crude oil. Mobil 1 and Amsoil are the best examples of these type of oils. They offer performance throughout extremes, resist oxidation, all kinds of fun stuff.

Group V is a blanket term for anything else, usually ester based oil. Red Line Oil is a common example of this.

 

[Rabbler]

Most of the mass market "synthetics" are predominantly group III I believe. Not sure about Mobil 1 though.

And don't even the 'true' synthetics have some conventional oil in them?

 

[Rabbler]

Is Mobil 1 really a grp IV? I'm talkin' regular 10w30 you can buy at Wall-Mart not some euro version.
I've heard so much [censored] about it I don't know what is what anymore.

 

[bmwtechguy]

My GUESS is that it has Group III and PAO (Gr IV) in its basestock blend. That being said, I still think it may still have a higher amount of PAO than some of the other retail synthetic brands. This is still just a guess. Does that make it better? Not for me. How the oil (basestock blend plus additive package) performs in any given app is what makes it better or worse. That's the key. UOA's, sound in your engine, fuel economy, consumption, all tell part of the story.

 

[MGregoir]

Mobil 1 is primarily PAO in all formulations. believe the extended performance has a greater concentration of group III to allow for the higher additive concentration versus the conventional blend. I believe that all blends of Mobil 1 are 70% or more PAO, and the lowest amount of PAO is in the Extended Performance products.

 

[Rabbler]

Well what I thought and believed for a long time is that it used to be mostly PAO but with the emergence of all the the cheaper grp III 'synthetics' they had reformulated and were mostly grp III as well. There is so much contradictory info and rumor floating around its so hard to separate the 'truth' from the 'lies'
Now I realise just because an oil is mostly PAO it doesn't make it the best oil for every application, but it would be nice to know what your buying.
As I'm involved in the education of professional technicians I try to be as accurate as possible and I get asked about oil a lot.

 

[MGregoir]

PAO doesn't blend well with additives, so esters or some mineral-based oil has to be added to help dissolve them.

Mobil 1 is primarily PAO, Mobil 1 Extended Performance is primarily PAO but has more group III content.

Mobil 1 for many years was a blend of PAO and esters.

Valvoline's SynPower is a blend of PAO and group III, mostly group III in all grades except the 20W-50.

Castrol Syntec except the German Castrol 0W-30 is all group III. GC is a PAO oil.

All Amsoil products are PAO except the XL-7500 line.

Basically all other "synthetics" are Group III oils in North America. Group III oils have shown themselves to have a lot of good characteristics, the negativity around them bases around the argument between Mobil and Castrol about what is actually synthetic. Castrol's argument was that group III is so processed it is no longer like the original stock it was based on, and is therefore synthetic, whereas Mobil...said synthetic is synthetic.

Castrol won, Syntec was legally allowed to be marketed as a synthetic, but the price stayed the same, and a bunch of people got bitter about paying the same price for what is a cheaper to produce product. Go figure, but it drug the reputation of Group III with it. If Group III oils were sold as the highest quality non-synthetic oil at a price point to match, they would be openly embraced by most, and oils like Shell Helix with Group III+ base oils perform exceptionally.

Once you get to Group III+, Group IV and Group IV oils, all perform extremely well when mixed with the right additives, and it becomes what is good for the application, not what is the best oil.

 

[Rabbler]

Thanks
That is mostly what I thought.
Sorry to the OP for taking over your thread... but it's kinda related.

I'm interested in accuracy but also for my own interests.
I remember when Syntec was the old formula years ago. (it smelled different)
And recently I've been extending my OCI (with Syntec)and the stuff has held up pretty well (backed by UOI)
I travel regularly to the US and can take advantage of some of the fantastic deals available and now It's got me wondering If I can get PP, Mobil 1, and Syntec for all around the same price what's the better choice. PP looks really attractive based on recent UOI's and price. Mobil 1 isn't usually a consideration based on the price we pay for it up here, same with the boutique oils.

 

[Drivebelt]

A couple of articles at Machinerylubrication on …"The Evolution of Base oil Technology" …explains things in a little more detail …

part 2

part 3