I just took my car to my local oil change spot and they told me that they wanted to use Mobile 1 Full Synthetic 0W40 versus the 5W30 that I usually get.

They told me that this weight is good for the European cars and that I was getting sludge from using the 5W30. I'm not very well versed in oil viscosity so I wanted to check with you guys and see what your take is. I just checked my manual and the three oil viscosity ratings that they mentioned in the manual was 5W30, 10W30 and 5W40.

Should I take my car back and make them put in a different rating?

Will running this weight of oil hurt my car?

What is the difference between the 5W40 and 0W40 oil?

 

Hi master_pre. The one thing I am certain about (from visiting BobIsTheOilGuy) is that nothing is certain. I get more confused than shopping for flowers. But I will say this, if you trust your oil change guy to work on your car then trust that he knows what viscosity oil is best for it as well. I can't say that one oil viscosity works for everyone because there are different conditions for everyone. But I imagine he took into consideration the mileage of your car, climate, and the type of driving you do. You have to remember that an oil change shop is somewhat liable if they recommend something and bad things result.

As for the 0W40 vs 5W40, I don't think theres much difference at all. There would be more difference between say 10W and 0W. The difference is on cold startup. Being synthetic, not much measureable difference.

 

Thanks for the response. I ended up going back and having them put the 5w30 back in and then the next change they said they'd have the 5w40 available. No big deal, I just figured I'd ask. Thanks for the opinion, and you're completely right everyone seems to have a different opinion on oil so I decided to stick with the Volvo recommended weight.