The new multigrade ran out like water when I drained my oil – why?
Compared with a SAE30 or 40, a 15W-40 may appear to flow more easily. This is more pronounced at lower temperatures. However, if comparing with another 15W-40, the difference can be due to a more effective performance additive package which prevents unwanted oil thickening by the soot or high temperature break-down. In other words, a high quality oil such as Shell Rimula X 15W40 or Shell Rimula Super may drain out more readily than an inferior product. This effect could be quite pronounced with engines that generate a lot of soot.
