EOLYS fluid is a fuel additive and is added to the diesel in the fuel tank by the EOLYS pump when needed to make the fuel and air burn in the engine run hotter, regeneration of the DPF requires exhaust gas temperatures of 600 degrees to burn the soot from the DPF.
The Eolys liquid pouch does eventually require replacement as original Xsara Picasso owners know all too well. I never experienced this problem myself on one of my previous cars, a 3.0D Jaguar XF, but other forum members were getting orange DPF warning lights, requiring an 'Italian tune-up' when they didn't do enough miles to complete the DPF . 386 360 0 138 170 334 359 384 258