Viscosity Index: by Bobistheoilguy (The man himself) "Temperature is a major factor when discussing viscosity of an oil. Visc has an inverse relationship with temperature Visc decreases with increasing temperature (the oil thins out) and rises with decreasing temperature (the oil thickens). The rate of change of viscosity with temperature change can be dramatic. Visc's are usually measured at certain standard temps, such as 40 and 100 degrees centigrade or celsius, which have proven useful in the selection of oils for different applications. In use, an oils visc varies depending on the temp at various locations in the lubrication system of the equipment. For example, it would be different in the piston ring area of an engine than in the main bearing area. So, the most common means of discribing an oils visc/temperature relationship is with an empirical number called the "viscosity index" or "VI". Again, the relationships are inverse. The lower the VI, the greater the change of visc of the oil with temperature. One of the reasons I made the oil analysis section is so you can really look at numbers on actual used oil so you can see that in some cases that the base stock is not what dictates a good oil but a combination of base stock and additives. I personally think redline isn't as good as what some say. The thing I'm not impressed with is first the price, and second it seems to carry a higher level of oxidation levels for the same milage as a competitor such as schaeffers that has the moly like theirs but only uses about 25%pao. I consider redline to be a specialized oil like schaeffers unlike maxlife and mobil. Do you Have you any ideas as to why a blend can hold up to what redline is doing? As for maxlife, as pointed out before, I'm not comfortable with the disulphate they use and wouldn't use it in my car for that reason alone, but also I'm not covinced yet that it can handle any extended drains because of the additive levels i have seen." just my 2cents worth. bob I always enjoy reading some of the original post. Still learning.