Titanium and stainless steel are both chosen because they resist corrosion, but they resist it in different ways, and the difference shows up in how they should be cleaned. Stainless steel relies on a chromium-rich surface layer that re-forms when it is disturbed; keeping the surface clean lets that layer do its job. Titanium forms its own stable oxide layer and is generally very tolerant of the environment, but it is more sensitive to contamination at temperature and to anything that leaves an iron deposit behind.
The practical consequence is that the same routine mostly works for both, but the metals differ in how they react to neglect. Stainless steel shows corrosion as staining and pitting where chlorides and dirt have collected. Titanium tends to look unchanged until it is hot, which is why keeping it free of contamination before it reaches working temperature matters more than cleaning it afterwards.
Wash with a mild detergent and plenty of water, then rinse thoroughly. The rinsing matters as much as the washing, particularly on stainless steel, because detergent residues and the minerals left behind after a wash can hold chlorides against the surface. A soft cloth or a soft brush is enough; both metals are harder than the cloth, so there is nothing to be gained by scrubbing harder.
For heavier deposits, clean in the direction of any brushed or polished grain rather than across it, and work in sections rather than soaking the whole part. An ordinary wash is usually all that is required to bring the surface back.
Avoid anything containing chlorides. Household cleaners, some bathroom products, bleach-based sprays and certain degreasers leave chloride behind, and on stainless steel that is the most common cause of avoidable pitting. Avoid abrasive pads and wire brushes made of mild steel too, because they leave particles of ordinary steel embedded in the surface, which then rust and make it look as though the stainless itself has corroded.
On titanium, avoid handling the surface with bare hands before it is welded, and avoid cloths or consumables that have already been used on steel. Contamination that is invisible at room temperature shows up as a change in the colour of a weld and sometimes as a loss of toughness.
Colour on titanium is an oxide film whose thickness varies with how hot the metal has been. It is not rust and it does not indicate corrosion. In a welded component the colour pattern along a seam is a record of the heat that area saw, which is why fabricators read it as a quality indicator. On a finished titanium exhaust system the same colour develops in service as the metal heats, and it is expected rather than a fault.
Stainless steel behaves differently. Some grades discolour with heat, and the colour generally stays closer to a straw or brown tone. Neither metal needs the colour removed, since polishing it off may look better for a while but it returns with the next heat cycle.
Finishes on these parts are chosen for a reason. Brushed and polished surfaces are easier to keep clean because less dirt catches on them, and the different finishes available on custom work change how a part looks as it heats. Whatever the finish, the useful habit is to clean before dirt has a chance to become embedded, and to rinse whatever you clean with.
Where a part sits close to the road, the biggest threat is not the metal but the salt and grit thrown up from the surface. Rinsing regularly, particularly after winter use, removes the material that would otherwise sit in crevices and hold moisture against the surface.
The metal usually outlasts everything attached to it. Gaskets, hangers and flexible sections age faster than the pipe does, and a leak at a joint, or a mount that has hardened, is a far more common failure than a corroded tube.
On a complete stainless steel exhaust system, the parts that deserve regular attention are the ones that flex: the mounts, the flexible couplings and any silicone components nearby. Silicone ages with heat and time, and a hose that has hardened loses the movement it was there to provide.
