letter no. 1
Should I use 5W-30 or 5W-40 in the UAE heat?
the desk replies — Use what your owner's manual specifies, including any GCC or hot-climate supplement. Many Japanese and Korean engines call for 0W-20 or 5W-30 even here, while many European engines genuinely specify 5W-40. Thicker oil is only worth considering for older, high-mileage engines with oil consumption, and then only within the manual's permitted range.