hope this site would provide yous some info regarding cold and hot plugs. it will also explain what type of plug is better for your vehicle. cold plugs is usually use for vehicle the travels long since engine runs hot for a long period of time it needs to cool fast. hot plugs usually use by vehicles that travels less like home-office and office-home. you can determine if the plugs are hot or cold by the numbers indicated on the part number of the plugs for NGK lower number like 6, 7 are hot plugs and 8,9,10 are cold plugs. for denso 11 to 18 are hot plugs 20 above are cold plugs.


http://www.globaldenso.com/en/produc...g_asia_all.pdf

http://www.ngkntk.co.uk/working/RunS...=ASP\Pg161.asp

this are sparkplugs catalogue free download.

http://www.ngksparkplugs.com/product...lugs/index.asp

this site provides you information

http://www.bosch.com.au/content/language1/html/5673.htm

here you can download bosch plugs catalogue