In the owners manual for my June 1994 corolla 1.3 gli with the 4E-FE engine it says that the spark plugs should be NGK BKR'5'EYA and the plug gap 0.8mm.
My local suppliers in his big book of plugs bible it says it should be a NGK BKR'6'EYA. He says my owners manual is 15 years old and things get changed. He says it's to do with the rate the plugs warm up. I'm not sure now which one to go for? Thanks for advice.
Go with the newest recommendation, the 6 is the heat rating (higher number is cooler running) There may have been problems with the 5's that has meant a change to a cooler plug was in order. For engine safety's sake it is a good idea to run the coolest plug you can that does not give problems.
Some extra details here, but not definitive advice...
How much of a risk of carbon fouling (ie running too cold) might there be in this kind of situation, if both plugs are specified? Is there any point in picking one over the other depending on usage - say a cooler plug for consistent motorway driving compared to a hot plug for frequent cold starts?
Theo
Not nowadays, years ago plugs had much narrower heat ranges and would burn or foul much more easily. Modern plugs, especially NGK are much more resilient. If you have a track day car then it might be worth going to a colder plug, or if you have an earliy efi fiesta that only travels two miles at a time then get a hotter plug. But for normal use just use the latest recommendation.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required