Unleashing the Power 10w30 vs. 10w40 Oil Showdown

10W-30 and 10W-40 are very similar, folks living in very cold areas may opt for a 5W-30 and folks living in extremely hot climates may select a 20W-40/50. ... 10W-30 (51). 10W-40 (26). 10W-60 (3). 15W-40 (25). 15W-50 (8). The higher the number after the w, the thicker the oil at high temperatures. It can be appropriate to change to 10w-40 if you are in a hotter ... The Owner's manual tells us to use 10W-30 oil, what would happen if one used 10-40? will this do any harm and why? In the 10W-40 engine oil, the 10W (W = winter) simply mean the oil must have certain viscosity or "thickness" flowing at low temperature. The lower the "W" ... 10W-30 oils had better base oils and less viscosity improvers due to the narrower spread in viscosity, which is preferable. Will you pick engine oil 10W-40 or 10W-30 for your car? Not every car driver know how to choose the best car engine oil for themselves. Both 10W30 and 10W40 oils are high quality and flexible, so they work well in cold and warm regions. However, there are some slight differences between the two. Scotty ... The car calls for 10W30, you won't gain any appreciable benefit using synthetic oils. You engine is suseptible to a number one main ... What is the difference between 10W40 and 10W30 oil? Yamalube®'s 10W40 ... Yamalube Oil vs. Castrol Synthetic Oil, and Conventional Oil ...