Quote:
Originally Posted by fe7565
Thank you and thanks for the comments from others as well. I already bought the parts, (coils and spark plugs) about a year ago in anticipation of any issues popping up, And the spark plugs have over 50,000 miles so might as well replace the coils as well.
The car is running great, so it seems a bit wasteful to make these replacements, Specially, in light that I haven’t decided yet if I’m going to keep the car for more than a couple of more years. At the same time, I don’t think a future owner would care to consider in the selling price a bunch of brand new spare parts on the side. So may as well do the replacement so the car in that aspect is good for another 60k to 80k miles.
|
I have had plugs replaced -- on the factory schedule -- a number of times with various cars.
At no time did the engine ever react favorably (or unfavorably) to the presence of new plugs.
To me this is a welcome behavior. The plugs were doing an adequate job until their change by date/miles.
The last thing I want to do is run plugs for so long the engine manifests any untoward behavior.
There is another consideration at least with some of my car engines. The factory called for plug changes at so many miles -- no surprise there -- or after so much time. A bit of a surprise, maybe.
But if one looks at old plugs -- I'll post a pic of some -- one can see the plug threads are discolored. This is from the slow creep of combustion by products being forced up the plug threads. These byproducts are corrosive.
There is the risk of upon removing the old plugs the corrosion results in further damage to the head threads.
Bad enough the plug threads get damaged but the head threads are in very expensive heads -- to state the obvious.
Just because the plugs are not manifesting any signs of age/deterioration does not mean they are not due to be replaced.
The plugs in the pic of from/for my 2002 Boxster. The used plug was removed -- along with the other 5 -- at 60K miles the mileage at which Porsche called for plug replacement. I don't recall if Porsche had a change by date for Boxster plugs. (It had a change by date for my 2003 996 Turbo.) I drove the Boxster a lot of miles per year -- on average 20K miles a year -- and plugs were changed every ~3 years.
I always used factory plugs. The factory plugs come with a *dry* thread treatment that helps ensure proper installation and accurate torque reading and yet doesn't result in any additional substance on the threads.
The risk is any thread lube can work to insulate the plug threads from the head threads and thus slow the flow of heat from the plug tip out through the threads of the plug to the threads of the head. The plug can run hotter which can shorten its useful life.
Some thread lubes (aluminum based IIRC) can be harmful to O2 sensors even catalytic converters.