Originally Posted by Rick
You would not beleive the intricasies of this subject. For instance, the "10W" of a 10W 50 has a different viscostity to the "10W" of a 10W 60.
In practice, with modern oils it is difficult to really get it wrong.
My (educated
) opinion:
Lots of cold start winter driving - 0W 40.
General all purpose - 5W 40/10W 50
Hard use, not too many cold starts, especially for engines with large clearances, 10W 60 (millers CFS is the best i have found)
Rick.
Im sorry but a 10w is a 10w and it has to be no more than a certain viscosity at -30degC (6600cp).
What is different is that a 40, 50 or 60 is a different viscosity measured at 100degC.
5w is better than 10w for cold start etc.
Multigrades
DegC...............0...............10............4 0..............100
0W/20............329............181...........46..... ..........9..
5W/40............811............421...........92..... .........14..
10W/50..........1039...........539..........117....... ......18..
15W/50..........1376...........675..........130....... ......18..
20W/50..........2305..........1015..........148....... ......18..
The "w" number is measured differently to the sae number (second/larger one).
0w is fine but slightly overkill in UK climate.
Cheers
Simon