I need to replace the battery on my 2005 Ford Focus. The battery indicated is a 590 CCA. I live in a very mild climate in Seattle. Rarely gets below 20 degrees here in the winter. Is there any reason I should go for a higher CCA or stick with the manufactutrer's suggested 590?
There is no reson to exceed the OEM requirement, or spend the extra money to purchase battery capacity you don't need. I think you need a BCI Group Size of "96R" ...
If you were running accessories with the vehicle off for extended periods, off-roaded the vehicle, or had a large lightbar, huge stereo amplifiers, or other add-on things, it might be a consideration.
I sincerely doubt you have any of these. Stick to the original group size of battery.
Note that different aftermarket batery manufacturers may have a different CCA rating for the same group size. You can safely ignore these slight differences.