last time i change my oil (5w) it was pretty hot out, about 3,000 miles ago. now its really cold out and i was thinking of changing the oil to 10w 30 since its cold out. is this neccesarry?

 

you have it backwards... 10W in hotter weather and 5W in colder weather. It is not neccesarry to switch, 5w would be fine all year round. 5W is more viscus in colder weather than 10W.

regards, Mark

 

You're back asswards. Using heavier weight oil in the summer helps to keep a good coating on the parts, since it won't run off at higher temperatures as much as a ligher oil. That assures you better cold start lubrication. You use a lighter oil in the winter so the starter doesn't have to crank over thick, heavy, cold oil. This means quicker, easier starting.

10W30 summer, 5W30 winter.

 

so that's how you guys change oil on the east coast...i dont' believe that applies to a state like CA right ??

Speaking of oil, wat's the diff. between 10-30 and 10-40 and when to use it
??

 

Use of different weights of oil depends on the temperature range you expect to see during the period between changes. California is a pretty temperature stable state, so you don't have to worry about it.
Viscosity. 10W40 is too thick for a Civic, not to mention the shear problems that a lot of 10W40's have.

 

I've actually used 0w-30 in the winter.

 

I've always just used 10w-30 in all weather since I have high milage (134,000).

Is is safe to use the 5w-30 in higher milage cars like mine? I was told to just stick to the 10w-30.

What about synthetic? I was also told to stay away from synthetic because of the high milage. True?