[Phelankes]

The car is a 2018 440i coupe.
Did the under warranty service from the Town Country BMW around one month before. The onboard computer showing the average fuel consumption becomes 14.6l/ 100 km now(Before just around 12.3l/ 100 km).
I looked at the engine hood, and it said this car should use 0W30 engine oil, but the Maintenance record paper they give to me noted the service put 0W40 instead of 0W30.
Have they done the right? Or am I worried too much? Will using different oils be bad for the engine?

I did a few times test: Fill up the tank and write down the current number of milages (a). Use the whole tank of gasoline. Come back to the gas station to fill up a tank of gas (x) and record the number of milages (b) again. Use the formula: x/(b-a)*100 and got 12.3 l/ 100 km.
From this situation, my car's fuel consumption is still about 12.3l/ 100km. However, the onboard computer is considered to be 14.6l/ 100km.
What will you do? Will you ask the dealer to get the oil back to 0W30?

First, Thanks for all the answers!

[paimon.soror]

I wouldn't worry about it. Your gas mileage may go down slightly as a w40 would require slightly more pressure to weed through the engine.... but its not going to cause your engine to blow up or anything.

Many of us on the forum willingly opt for a 40 weight depending on the oil brand since some 40 weights use a better base stock than their 30 weight counterparts.

[SC_B5X]

Originally Posted by paimon.soror

I wouldn't worry about it. Your gas mileage may go down slightly as a w40 would require slightly more pressure to weed through the engine.... but its not going to cause your engine to blow up or anything.

Many of us on the forum willingly opt for a 40 weight depending on the oil brand since some 40 weights use a better base stock than their 30 weight counterparts.

This. Using higher weight oil wont hurt.

B58 is approved for 0W-20, 5W-20, 0W-30, 5W-30, 0W-40, and 5W-40 per the owners manual. So as long as your using one of those you'll be good. I'd recommend a thicker oil if you are tuned, such as 5W-30 or 5W-40. I personally use Motul 8100 X-cess 5W-40, the only downside of thicker oil i've noticed is it decreases your MPG.


Screenshot from the BMW Owners Manual

[Mkswoosh]

Another thing to consider to the response above is temperature of the location and brand.

[paimon.soror]

I'd say in toronto he has to worry more about the cold weight hehe