Have an 05 Audi S4 (B6).
Previous owner said he used 0W ??, while the auto parts store said that for this model, you can use 0W or 5W and that you can interchange with no issues.
My understanding is that the lower the number before the
W, the thinner the oil is.
Does it matter if I live near the Rocky Mountains (higher altitude) or anything?
I would like to just stick to one, which weight should I go with?