Originally Posted By: SonofJoe
As per usual, getting hold of information to make a judgement on whether Shell HX8 5W30 is any good isn't easy.
I found this that someone had posted earlier on BITOG...
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3587706/Shell_Helix_HX8___5w-30
It doesn't tell you much but the sub-12 KV100 does suggest this stuff is OCP VII based. Shellvis based oils can really struggle to meet 3.5 min HTHS and it's not unusual to see KV100's of 12.3 to 12.4 (ie very close to the 12.5 max limit) to make the oil barely on-grade.
Tech-wise, the profile looks at lot like what you get from Afton's Hitec 9490 12.6% additive pack in full Group III.
Here's the link to get the Hitec 9490 PDF file so you can compare for yourself...
http://www.aftonchemical.com/Solutions/EngOilAdd/Pages/PassengerCar.aspx
So my considered opinion, given the absence of any definitive data whatsoever is yes, HX8 5W30 is probably an okay kind of oil. If it's cheap, then it ranks very high in my book and I'd probably buy it.
Yes of all the synthetic 5W-30 A3/B4 oils I can easily get here, the Shell HX8 stands out as having the lowest KV100 at 11.9 with Castrol Magnatec at the other end with a KV100 of 12.2 cSt.
So correct me if I'm wrong, but OCP is efficient and cheap and adds to HTHS but is more prone to shear, while Shelvis is expensive and shear stable but less efficient and adds less to HTHS.
Anyway I always thought, that for a given HTHS the oil with the lowest KV100 was better as it had the lowest VII load. An oversimplification I know, as it ignores shear and thermal stability. That polymer efficiency Va shear stability makes life hard, as you want both, but from what I can tell they appear to go in opposition to each other (ie you tend to swap one for the other).