10W30 vs 10W40 Deciphering the Numbers for Optimal Engine Performance

10W30 and 10w40 are very similar oils. Both oils are flexible, multigrade oils that perform well in different temperature ranges. +1 for 10W40, or even 5W40 if you live in Texas. Here in AZ where we see winter temps at 6am of about 25F, and summer temps at 3pm of 120F, it's worth it. 10W40 oil for the Tour DCT rather then the 10W30 the manual states. Has anyone been using 10W40 and if so, have you noticed any difference in performance? The 40 weight will protect you year round for what you do;-it only has certain factors to the heat build up;-ambient temp and other component ... This video offers an in-depth comparison between 10W-30 and 5W-40 engine oils, analyzing their viscosity ratings, characteristics, ... 10w30 and 10w40 are multi-grade oils this means that they can carry properties of different weight oils depending on the conditions. ... 10W-30 API SL. FULLY SYNTHETIC 0W-20 API SN. SERVICE CENTRE & HIGHSTREET. Availability: 3L & 3.5L 3L 3.5L. Excellent wear protection with enhanced antioxidant ... It's sorta like viscosity, but with a difference. People traditionally talk about 'weight' of a motor oil. The numbers 10, 30, 40 are oil ... 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? If your engine specifies 10W30, using 10W40 won't present any changes. It's just a little thicker after the engine has warmed up, and will ...