The longevity of muffler and pipes depends
on what kind of steel the components are made of, how pipes are routed
under the car, where the muffler is located, and whether or not the
vehicle has a catalytic converter.
Original equipment pipes made of aluminumized
steel generally last five to seven years, except in areas with a lot
of road salt and moisture. In these areas, pipes may need replacing
after three to five years.
Original equipment pipes made of stainless
steel (which are used from the converter forward on most cars and for
the entire exhaust system on some) can last up to 10 years or more.
Most aftermarket pipes, by comparison, are
made of ordinary steel which is good for about three to five years of
service. Aluminumized and stainless pipes are better, but cost more.
With mufflers, stainless holds up the best,
followed by doublesided galvanized steel. Single-sided galvanized and
aluminumized hold up fairly well, while plain steel offers little or
no corrosion resistance.
As a rule, the hotter a muffler runs the
longer it lasts. Mufflers on vehicles with catalytic converters run
hotter and last longer than those on older vehicles without converters.
Mufflers located ahead of the rear axle last longer than those located
aft of the rear axle.
Mufflers rust from the inside out. Rust is
caused by moisture in the exhaust. Moisture condenses in the muffler
when the engine is shut off and the muffler starts to cool. Some mufflers
have a small pin hole that allows condensation to seep out.
One aftermarket muffler manufacturer puts
a small packet of a special moisture absorbing chemical inside some
of their mufflers to fight internal corrosion.
A muffler that needs replacing is an opportunity
to sell clamps, pipes, hangers and any special tools that might be needed
to complete the job.