hi everyone. i wanna start using 5w-40 synthetic for my honda civic lx with 252k switching from 10w-40 over winter months, for better protection and wanna know if castrol synthec is good or maybe mobil 1 5w-40. i would use redline over this those two, but red line is bit pricey for my budget. what would be really good synthetic oil after red line in range 5w-40 for the price and quality? any answer/opinion is welcome. thanks....