Quote Originally Posted by yebo
stupid question: ano difference ng BKR5E and BKR6E ngk plugs? tagal ko na suspect kasi na mali yung plugs na install ng shell gas station sa car ko because ever since they serviced it the mileage went down. last thursday, wala ako ginagawa and on my last day in pinas (went back here in indonesia last friday) i decided to pull out the plugs. ayun BKR5E naka-install, manual says BKR6E. could this be the cause of my low mileage? 34T km on the odo pa lang so far and the first 30T km the mileage was purty good, until i had it serviced.
higher heat range sya... meaning, the plugs are colder...

Colder plugs are usually used whenever you do some major engine upgrades (like higher compression ratio or going forced inducted).

On stock engine, better stick with the manufacturer specified heat range... Higher heat range plugs are more prone to fouling (if higher is used compared to recommended, although better if you always stay on higher revs). On the other hand, going for lower heat range promotes detonation...

Cold plugs = high heat range = disperses heat much faster = usually higher number sa part number ng plugs
Hot plugs = lower heat range = disperses heat slower

(ex. for NGK BKR7E = 7 is the heat range number, so it has higher heat range compared to BKR5E)