most likely PAO and Group II
Thoughts on GTL base stock synthetics?
- Thread starter Retirednow
- Start date
Hm, interesting, i thought all SHU oils all had mostly GTL in them.
Seems you do not bring anything new or old then to the debate except your statement. Now that GTL competes with PAO on VI can you tell me any negative issues with PAO?
OVERKILL
$100 Site Donor 2021
PAO has higher oxidation resistance and better cold temperature performance, so it's better at both ends of the extremes range. For your typical application? Neither of those things will likely be relevant, though the oxidation resistance does help with extended drain capability, which may be some of the reason we see it in M1 EP oils.
OVERKILL
$100 Site Donor 2021
Unlikely, SOPUS tries to avoid using PAO. Historically, they've used their XHVI base oils (their Group III precursors to their GTL bases from Pearl) and they still use them, though I think a bit less now, because they have a broader range of viscosities from what I recall.
Now, the Euro SDS sheets don't show anything useful, and neither does the US Pennzoil Platinum Racing SDS, however, the older Pennzoil Ultra Racing 10w-60 SDS does show the following, lol. So, 0-90% GTL, hahahah
No mention of PAO though. I know 0W-40 Rotella T6 used to indicated that it was mostly polyolefins on the SDS, the newer SDS calls out 10-15% but then says 0-90% interchangeable low viscosity base oil, so probably GTL
OVERKILL
$100 Site Donor 2021
Yep, 0w-40 seems to be one of those grades where PAO is pretty much necessary. As I said, Shell tries to avoid using it (so does Castrol). Mobil is the only large one that seems to use it willy-nilly all through their product portfolio, but then they are also one of the world's largest produces of it, so that makes sense.
There is nothing new to bring. I dont feel like repeating the benefits of PAO that were mentioned many times before. The only negative issue of PAO is its 3 times more expensive than GTL
https://www.machinerylubrication.com/Read/31106/polyalphaolefin-pao-lubricants
additive solubility, needs another base oil to blend additive package.
Seal shrinkage risk…
Limited biodegradable.
and cost.
additive solubility, needs another base oil to blend additive package.
Seal shrinkage risk…
Limited biodegradable.
and cost.
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GTL and PAO are both very non-polar base oils and are both really poor in terms of additive solubility.
OVERKILL
$100 Site Donor 2021
Group III has the same poor solubility issue, but isn't as hard on seals. As I noted in my earlier reply to you, the main benefits of PAO are extreme cold temperature performance and high temperature deposit resistance/oxidation resistance. This is why you'll see it used in certain grades from blenders that typically avoid using it.
PAO has historically been blended with POE to get the proper seal compatibility characteristics. This has the advantage of improving solubility as well. POE of course has some advantages, but like PAO, is expensive, so now you've made your expensive base oil blend even more expensive! The alternative is to use AN's, which also have good solubility. Mobil's old "tri-syn" formula was exactly that: PAO, POE and AN's. So, you got a very robust base oil blend with good solubility, high heat handling and oxidation resistance, but of course that 's a pretty pricey setup!
Group III doesn't have the same issue with seals, so it doesn't need POE or AN's. So, the overall blend can be much cheaper to formulate with just the inclusion of a carrier oil for solubility of the additive package, which itself has the elastomer compatibility (seal conditioner) additives as part of it.
I think gtl being on similar level as pure paraffinic oil. It shouldn't be as bad as pao
OVERKILL
$100 Site Donor 2021
The rule of thumb is that the higher the level of processing, the lower the solubility; the "dryer" the base. You can't just go by group number, because of course Group V bases (esters like POE, AN's) are incredibly polar and have incredible solubility.
So, the least refined of the base oil groups, Group I, is quite polar and has great solubility, but it also will produce deposits, has horrendous oxidation resistance and extremely poor viscometric characteristics. You step up into the hydrocracked bases, which are Group II and III (though you can have a solvent-dewaxed Group II) and the more severe the base is processed; the more pure it becomes, the better its viscometrics, but it loses its polarity and solubility; it becomes more like PAO.
The difference is primarily in the seal compatibility department (though Group III has slightly better solubility than PAO, but it isn't much) where PAO will shrink seals, and this has to be counteracted with something else, which, as I noted in my earlier reply, has typically been POE, which, by itself, has the opposite tendency, to swell seals.
So you must have ester, an, if you want really well dissolve the additives?
Is still worth to make gr1-2 oils? Who's using it anyway?
I thought everyone upgraded their refinery at least one notch
Is still worth to make gr1-2 oils? Who's using it anyway?
I thought everyone upgraded their refinery at least one notch
OVERKILL
$100 Site Donor 2021
Lots of Group I and particularly Group II still out there. A mix of solvent dewaxed and hydrocracked. Mobil sells their EHC bases, which are "Group II+", hydrocracked, extremely popular, used in a number of the Dexos oils.
Originally, I don't think Mobil used AN's, that was a more recent development, when tri-syn came out. Before that, I think it was just PAO and POE. AN's likely enhance the solubility of the overall formula further still, while not having any negative impact on seal swell, like too much POE would. It's a balancing act, and I'm not a formulator, but that's my understanding of the synergies. AN's compliment PAO quite well, and the dose doesn't have to be high, which is good, because AN's are low VI.
Unimportant within the confines of a relevant license or approval.
Oxidation and deposit resistance for one thing as Overkill notes. It was well illustrated on the Visom presentation.
Some more info… PAO is lowest on the scale of lubricating and additive solvent due to it’s non polar nature.
https://www.lube-media.com/wp-conte...lsposeachallengeforsolubilityandlubricity.pdf
This is from 2009
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OVERKILL
$100 Site Donor 2021
Yes, and this little chart on the first page shows what I stated earlier, that the more severe the hydrotreating, the more the oil behaves like PAO.
