Originally Posted By: CharlieBauer
Hi Joe, can you explain what those sloppy blending tolerances mean and the negative effects they can have in everyday use?
Is there anything else wrong with the oil we get? And is there any way to get better quality oil eg would the country of origin help or do they make special subpar versions for us anyway making COO irrelevant?
Oil has to meet a lot of specifications, the most basic of which is SAE J-300 which defines the oils viscometrics. If, for example, you pick a 5W30 (the most common oil PCMO grade in the US) it should have a KV100 of between 9.3 and 12.5 cst and a CCS-30 of less than 6600 cP. Now whilst this gives you a lot of freedom in the way you blend the oil, logic would dictate that you blend an oil that has a KV100 of 9.31 cst and a CCS-30 of 6599 cP. Why? Because this oil would contain the least amount of VII polymer and the lowest Noack. Not only are both these factors good things in their own right but both impact directly on the cost of the oil, so you have in built economic incentive to blend the oil this way.
There are all sorts of reasons why such tight blending isn't feasible. As well as KV100, the oil has to meet a minimum HTHS spec of 2.9 cP. Just for the sake of argument, let's say, to get a 2.9 cP HTHS you have to make an oil with a KV100 of 9.5 cst. In industry parlance, HTHS becomes the limiting spec and KV100 'floats'.
Also commercial blend plants aren't sophisticated places like laboratories; they just blend to a pre-defined 'recipe'. They need some 'slack' to account for variations in base oil & additive quality. So maybe they make an oil which has a KV100 of 9.7 cst and a CCS-30 of 6400 cP, which, although this causes the oil to include more VII, have a higher Noack and be more expensive to make, is fully justified.
And then there are engine test reasons why you might need adjust the blend further. For example you might need a higher HTHS to pass a wear test or a lower CCS-30 to pass a fuel economy test. This is all perfectly reasonably.
However it's when things go way beyond this for no good reason (something I see a lot on PQAI) that I think people should sit up and take note. Having an oil with a much higher KV100 and a much lower CCS-30 than technically necessary, makes for an oil that is not only more expensive than it needs to be but is also a WORSE oil because of it's high (IMO opinion, often ridiculously high!) Noack and high VII loading.
Strangely enough, for what is supposed to be the world's most dynamic economy, my experience of dealing with the US is when it comes to engine oil, it is incredibly resistant to change. To me, it seemed like it was still stuck in the 1970's and had to be dragged kicking and screaming into the next century!
BTW, this isn't rabid anti-American criticism. Just a distillation of what I saw and experienced over many years..