My pleasure Spaceman. My intention is just to help you see through the marketing smoke and mirrors of lubricating oil blenders. There's no magic involved, and if you break down the process you'll understand why different oils appear to have different properties.
They start with the base oil: a G-III, or G-IV, or GIII+GIV, or GII+GIII. They're homogenous when purchased from the producers, especially G-IVs. Then they add a cocktail of additives depending on what product characteristics they want to achieve. There are the detergents, dispersants, anti-oxidants, anti-foamants, etc. Then they achieve the target viscosity with viscosity modifiers, which are polymer thickeners. So they get the hot weight (eg 30 or 40W) which is the weight at car operating temp of 100C. This is the important figure.
Then they add Pour Point Depressants to achieve the cold weight (eg 0 or 5W) which determines the viscosity when you start the car. Pour Point is the temp at which the oil solidifies. At the risk of being flamed again
0W is really for arctic conditions. As we are about as far as one can get from the arctic circle, 10W is fine for us, even 5W is overkill. OW is marketed because it appeals to our kiasu-ness (lower must be better wor), but you're really just paying for PPD you don't need.
Then they add the friction modifiers, eg zinc and Molybdenum compounds. That's why some oils feel 'smoother' than others. But there's a drawback, the heavier the friction modifiers, the heavier the pollution emitted and the shorter the life of your catalytic converter.
So there's really no magic involved - it's a chemical cocktail mix. The most important consideration is - what's the base oil. That determines the longevity and sludge risk. The rest are 'feel good' factors.
No, I'm not a chemical engineer or O&G man. I just have an interest in marketing models, and the O&G models are among the most interesting around. :wink:
