Quote:
Originally Posted by brainrain
Nissan dealer in south of France recommend 5w40.
I was a little surprised because all people in this forum recommended 5w30 oil, despite the high temperatures in summer in the United States.
I discussed with some owners in France, most use 5w40. But we aren’t many to have a feedback on the reliability of the engine with this oil.
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How many auto engine engineers work at the dealership?
As the chart above shows, once the temp gets over 100C or so, the difference in viscosity is very little and which viz you use is not that important.
Below about 60C, the difference in viz can cause higher pressure, more strain on the oil pump, and a little less flow through the system. Moving up 10 probably won't make much differerence unless you really push the engine when cold, but why risk it.
This is for DDs. You track guys operate under different conditions.