Originally Posted by C4llyT

Search for oilman posts, should be answers there.

Basically how thick it is hot and cold, first number refers to cold flow.

Why I don't go higher than a 5, want oil thin to get round and protecting quickly.

Lorries at work have 15w40 and it's like treacle, fuck that.

To me 5w40 is all you ever want/need, happy medium of all qualities required.