Originally Posted by
phil alvirez
from wiki:
The number before the 'W' is the 'cold' viscosity rating of the oil, and the number after the 'W' is the 'hot' viscosity rating. So a 5W40 oil is one that behaves like a 5-rated single grade oil when cold, but doesn't thin any more than a 40-rated single grade oil when hot.
then see post 5. i ended up using pennzoil euro platinum. from the study mentioned at the post, pennzoil does better than mobil. and i think choosing 0 or 5 is not critical after all.
depends mostly of the temps where you are, the availability and offers. what am using is this:
Pennzoil 5W30 Platinum Euro Synthetic Motor
the specs here show several options of the euro for cars like the crossfire
https://bevo.mercedes-benz.com/bevolisten/229.5_en.html
0W40, 5W30, 5W40
This is good info describing multi-grade oils. What I like to remember is a multi-grade has a "flatter" viscosity curve versus operating temp than a single weight oil. In other words, with the use of additives, the oil companies can enable an oil to better maintain its viscosity with increasing operating temp.