A muffler of the average car is simple only from the outside. In fact, it is a rather complicated design, intended by engineers to work in a particular car.
The exhaust system includes not only the muffle shell but also the exhaust manifold, the catalytic converter, the exhaust pipe and the mufflers themselves - primary, center, and rear.
The internal filling of mufller is a complicated system of partitions and perforated pipes, supplemented by a heat-resistant sound-absorbing stuffing. The service life of these parts is predetermined by the design, quality of the production and materials used when creating a muffler.
The wear-out of the muffler during the operation of the vehicle takes place both outside and inside. The main enemy of this component is water, which arises from the deposition of condensate on internal surfaces and which comes into contact with the chemical elements contained in the exhaust. As a result, acids are formed. A high temperature acts as an additional catalyst in the process of oxidation and thinning of the parts of the exhaust system. Contrary to popular belief, a muffler is destroyed mainly not from the outside, but from the inside, that's why the external painting and protection of the body almost does not affect the real life of the part.
There are a lot of all sorts of recommendations in an online environment supposedly capable of extending the life of car mufflers. Most of them are limited to painting them with heat resistant paints and pouring inside the "miraculous" compositions on the basis of used oils and graphite lubricants. Alas, in reality, all these methods have practically no effect on the service life of the system.
The greatest amount of condensate appears in the exhaust system at temperature differences - during the warm-up of the engine and after you muffle it. The higher the temperature difference between the warm condition of the system and the ambient temperature, the more water accumulates in the system. The life of the components of the exhaust system is determined in many respects by the number of heating/cooling cycles. We also do not recommend to misuse the programmable remote starting in the winter for the same reason.
Any external damages of the muffler arising during the operation of the vehicle are potential sources of accelerated corrosion formation. Rubbles, sand and, especially sudden changes in temperature lead to the undercut of welding joints at the seals of components, which reduces the life of the muffler.
When repairing the exhaust system, use only high-quality components made of the right materials, from serious manufacturers. Black steel, folds on the pipes, curved welding joints and low weight of the system are the reasons to refuse to purchase dubious products. Only reliable components serve for a really long time, especially when it comes to a car muffler.