Hi,

I plan on buying some mobil 1 tomorrow but cannot decide on which viscocity to purchase? 5w30 or 10w30? I live in MA and the summers do get hot and I do alot of driving. Same viscocity in the winter??

Thanks for your suggestions!!

64,000 miles

1998 S70 T5M

Hi,

You should do fine with 10w30 all year long. I'm in Canada (remote area close to Ottawa) and use 10w30 Mobil 1 even during the harsh winters. This past winter I've put in 5w30 in my 2000 XC to see if I could see a difference on cold starts from the previous years but barely noticed any improvement. All I can see is the pumpability index being better with the 5w30 but it has to be butt cold (-50F and colder) before the 10w30 starts to get thick. Given the heat ouput generated from the turbocharged engines, I tend to prefer 10w30 grade which sustains a much higher temperature.

There is almost no difference between the two grades at higher temperatures. That's what the "30" in 5w30 or 10w30 is all about. Viscosity at 100C is almost identical. If you want more protection at higher temperature use 0w40.