David C said:As said above, you can mix almost any modern oil.
However, neither of those oil is the correct grade for that engine!
Yes, but it is a different viscosity when cold!symonh2000 said:5W-40 should be ok in that engine as a 10W-40 is specified. It is the same viscosity when hot.
That doesn't make any sense, does it? If the pump can't pump the oil when cold because too thin, what will happen when the oil heats up, and it gets thinner again by a factor 10?David C said:Yes, but it is a different viscosity when cold!
It is just about ok though as they spec a 5w30 for extreme cold climates, so the oil pump can take a 5w oil.
If you drop to an oil that is too thin then the oil pump can't pump it any more and you loose oil pressure, not good!
I think a different method is used to calculate the two.Cuore_Sportivo_155 said:That doesn't make any sense, does it? If the pump can't pump the oil when cold because too thin, what will happen when the oil heats up, and it gets thinner again by a factor 10?
a 0w-40 oil, even being a full synth, will be doped quite a bit with viscosity improvers. These are widely known to be with the first dopes that fail in any motor oil engine, resulting in what will likely be closer to a 0w-30 oil. Obviously this isn't the right viscosity at all anymore (10.9 cSt average for SAE 30, 14.4 cSt average for SAE 40). That would obviously cause quite a bit of consumption.David C said:I think a different method is used to calculate the two.
Try a 0w oil if you want, but keep plenty in the boot as you will need to top it up very frequently.
I would be questioning them as to why they insist you use their oils when one of those oils has the wrong viscocity for the engine. I don't know what your climate is like so I may be off, but I would dump the 15w-50 and fill with a 10w-40 of a brand which is readily available, or selenia 10w-60 if you are going to use the same people next time.trento said:nothing much i could do. the agent over here did not carry 10w-40. they only have 15w-50shell or selenia 10w-60. i suppose u could go higher than 40 but not lower. also, they insist i must use their given oils so i went with shell thinking i could get it anywhere. but when i checked out the petrol stations, they are actually carrying only 5w-40. guess i gotta go back to the agent to get that 15w-50.