Can you explain engine oil weights?
May 7, 2007 9:49 AM Subscribe
Can someone explain the importance or relevance of different weight engine oil? How much and why should your local climate affect your oil choice?
posted by mdion to Travel & Transportation (9 answers total) 2 users marked this as a favorite
[Sorry if this has been posted before...I couldn't find a relevant post.]
I've read that the first number is the viscosity when the engine is cold and the second is the viscosity once the engine is warmed up. Why does viscosity matter?
Does the difference betwen 10Wxx and 5Wxx really only matter in cold climates?
And the difference between xxW40 or xxW30? Does that part not vary according to climate since it should be the same once the car is warmed up?
How does viscosity affect engine life and car performance?
I have a '03 Jetta and the owner's manual recommends 5W40 or 5W30. My VW mechanic (who I trust and respect) recommends a different weight during the summer in Texas (though I can't recall what weight at the moment).
So, if I'm driving my car through the Mexican desert, [how or] should I adjust my engine oil?
If I'm taking a road trip to Michigan in Februrary, [how or] should I adjust my engine oil?
Oh. And I always use synthetic oil...so are these issues different for synthetic vs. regular oil?