Unlocking the Engine's Potential 10w30 vs. 10w40

Not so much for the heat reasons, but because the oil brand I purchase is only available in 10w40 weight. So short answer, there is no ... Motor oil grades like 10W-30 and 10W-40 refer to the oil's viscosity, or how easily it flows, at different temperatures. 10W30 is a thinner oil and flows more easily at lower temperatures than 10W40. This makes it a better choice for colder climates. The main difference between the Castrol Edge 10W-30 and Castrol MAGNATEC 10W-40 lies in their high-temperature viscosity and their targeted use. In this matchup, 10W40 oil is slightly thicker than the 10W30 variant. The high-temperature viscosity plays a crucial role; remember, the higher the number ... As others have said you can use both grades in any Honda bike however if you run 10-30 you may see better mpg since 10-40 is a slightly heaver ... The bottom line is the 10W-30 is fine unless you expect ambient temperatures to approach or exceed 30°C (86°F) when you'll be better off with the 10W-40. Engine oils are divided into categories or grades based on their thickness level. The higher the grade of the oil, the thicker it is. The only time you have to even consider going to thinner oil when it gets cold is if the starter can't turn over the motor fast enough to start the motor. 10w30 is a more all year oil for a very broad range of temperatures. It has more protection for lower temperatures than 10w40 at the cost of being not as good ...