Can I Mix 10W30 and 5W30? Most Oils Will Mix Perfectly, Provided They Have a Similar Synthetic. Therefore, There Is No Problem in Mixing 10W30 and 5W30 Since...
Can I Mix 10w30 and 5w30? Most oils will mix perfectly, provided they have a similar synthetic. Therefore, there is no problem in mixing 10w30 and 5w30 since one will be topping up. Mixing the viscosity of oils will not have any effect on the engine.
What happens if you put 10w30 instead of 5W 20?
Notwithstanding the recommendations of the car manufacturer, mixing 10w30 and 5w20 will not cause any sort of harm to the engine. However, a few drivers claim that it is safer to combine two multi-grade or straight weight oils, rather than mixing multi-grade with straight weight oils.
Both the oils have similar viscosity at 100 degrees Celsius but 5w30 grade oil will thicken less than 10w30 grade oil in cold climate. This means 5w30 grade oil will flow effectively in low temperatures, whereas 10w30 oil will flow effectively in high temperatures because of the smaller temperature window.