Prompted by a tech tip in Moss Motoring, I wrote a reply, copy to the MG
list & several others, that blindly using anti-seize on spark plugs was
not a good idea. To summarize, Champion spark plugs have an anti-seize
coating from the factory & other products are not recommended. Perhaps
other spark plugs do also, I do not know. Never use any coating without
consulting the owners or repair manual first. Many dry coatings now
exist & may be present on aluminum cylinder heads that may render
anti-seize redundant, at best.
I am not saying that anti-seize should not be used, only that caution
should be used first.
The other point that I tried to make was that there are 2 grades of
anti-seize, low temp & high temp. Low temp is great for suspension
bolts, not good for exhaust manifolds. High temp is more expensive, but
can be used every where.
The original problem that Dave had where the spark plug had aluminum in
the threads is a common indication of cross threading. This is easy to
do with an aluminum head. The shop manuals & some spark plug boxes
contain installation instructions that few bother to read. Spark plugs
are to be threaded by hand until they reach the seat, then are turned a
further amount dependent upon design & the use of a gasket. It is
impossible to cross thread by hand unless King Kong shrinks his fingers
to fit a little spark plug in an often hard to reach location. The plug
holes should always be chased & blown out before installing new plugs.
The best mechanic I ever knew tried very hard to teach me a little of
his skill & knowledge. "If its hard, you are probably doing it wrong."
He must have told me that a hundred times, & it certainly applies to
starting threads in aluminum.