[aedcce]

I noticed local dealers use 5W30. I found no problem, but since my area is really hot during summer- usually temperatures stays around 105+ or 32+ during the day. Will using 5W-40 be little more beneficial for my N51 engine?

60k mi, so not super high mileage engine- but 90% in-city stop and go situation.

[DanG]

5W30 motor oil is suitable for temperature range of -25C TO +25C

5W40 motor oil is suitable for temperature Range of -25C to +35C.

https://www.oil-store.co.uk/blog/wha...0is%20superior.

[freakystyly]

Isn't the upper temperature range dependent to the car's cooling system? Operating temperatures are more than double ambient.

[BlkGS]

Originally Posted by freakystyly

Isn't the upper temperature range dependent to the car's cooling system? Operating temperatures are more than double ambient.

Yes. Oil's max temperature will be determined by the effectiveness of the cooling system, whether that be an oil cooler, or hea transfer via the engine to the coolant.

If you're not racing the car, temperature should stay relatively consistent from like 60-100F. If the car runs significantly hotter in summer, your cooling system needs checked. Your radiator and fans should be able to keep you at a relatively consistent temperature.