DRIVERS ASK, TOM ANSWERS:

MAINTENANCE PROBLEMS SOLVED

Tom,

Q I own a 2008 Buick Enclave AWD. It has a 3.6-liter V-6 engine in it. The

maintenance schedule says to replace the sparkplugs at 100,000 miles. Is this
correct or a misprint? I have never let a set of sparkplugs go that long. Please
advise.

John—Willingboro,   New Jersey

John,

A I double-checked the maintenance schedule for your truck. The stated

replacement interval in the schedule is correct. I too am uncomfortable with
this recommendation. Especially when you consider the negative
ramifications of leaving sparkplugs unattended for all that time. When left in
the engine unattended for a long time, sparkplugs tend to get dirty from
inefficient combustion of fuel. This results in carbon buildup. If the engine is
given to oil consumption, sparkplugs get gummed up and heavily carboned
up from oil spillage on the electrode. Finally, when left in a long time, the
dissimilar metal of the plugs and cylinder head react to each other, resulting
in the sparkplugs literally welding to the heads. This makes replacement hard
and in a lot of cases, cylinder head replacement necessary because sparkplug
threads are stripped out when removing old plugs that have wended
themselves to the head.

I recommend removing the plugs every 20,000 to 25,000 miles,
cleaning and re-gapping them, applying a never-seize thread compound to
them, and reinstalling them and properly torquing them to factory specs. This
will avert any sparkplug nightmares that might arise from leaving them in too
long unattended.