Manufacturers have specific guidelines for the size and capacity of the battery required for your car. The only choices you really have in buying a battery, are deciding the brand and length of warranty. Reserve Capacity Rating - This is the time required to reduce the charge of a fully charged battery to below 10.2 volts at a rate of 25 amps per second at 80 degrees ferinheight. The reserve capacity rating appears on the battery as a time interval. For example a rating of 100 minutes means that once the battery indicator lamp comes on in the dash the driver has one hour and forty minutes of driving time before the battery is completely drained and the car dies.
Cold weather is the number one killer of car batteries.
It slows the chemical reactions in the battery, making it harder for the battery to hold a charge. In general, using higher-octane gas does not increase performance or gas mileage for most cars. However, certain high performance and older cars do require it. If your car is one of these, your owner's manual should contain the minimum octane rating for your car. The only other instance in which you might need higher octane, is if your car knocks or pings.