Re: [DML] re: sparkplugs

[dherv10@xxxx]

Kevin, Your reply was cut off at ,,If i'm concerned about: Here's the rule of 
thumb about spark plugs. Not knowing how or why the engineers chose the 
temperature of the HR6 plug which is the coldest of the series. In the pre 
sensor and ECU days you could judge a cars proper burning condition by the 
plug. I have a list of 12 different things that a spark plug can tell you. 
Normal is the insulator tip is greyish white/brown or yellow. This tells you 
the heat range is correct for the type of driving your doing and how the car 
is operating. If you start getting the velvet look/black carbon deposites on 
the insulator then the heat range may need to be changed if your driving 
conditions don't change.I hear most people driving the cars on short hops and 
combine that with a sensor that doesn't pre heat and all this adds a richer 
gas mixture in the cylinders and not long enough drives to burn off the 
deposites. The simple answer is to go to a hotter plug based on your driving 
conditions. I'm sure the HR6 plug is adequate for most driving conditions for 
most people, but I'm from the old school and reading the plug I find i'm 
going to a hotter plug. The start and stop driving conditions on the Dallas 
freeways is the reason. Also, As the engine gets older and it begins to burn 
oil, the problem will escalate.
Hopes this help on the plug choice.
John Hervey