I want to get the best thing for my engine, but dont really know whats the deal with all the numbers, and why some are colored in a box and others are just plain. What does it mean?
I used the 10W 30 (with the green box) on my car regularly. But I decided to switch to 10W 40 for a better performance, but I was wrong. its even worse. Now I'm thinking of trying 5W 30, to see if I just went the wrong way with the numbers. But I really would like to know whats the big deal about them.