Thanks. I had assumed so, but what is it insulating? Would it degrade being soaked with used engine oil? Much the way a fuel leak will mess with rubber hoses and belts. Just curious, besides the fact that they messed up my spotless engine.
Well, the insulation is wrapped around the EGR (Exhaust Gas Recirculation) pipe, which basically feeds exhaust directly back into the intake. This is designed to slightly deprive the engine of oxygen to cool down EGTs to lower NOx emissions. Keep in mind, the Passat hardly uses this system (though it does use it a little) due to the fact it uses urea to clean up NOx in the exhaust, rather than using excessive EGR to suppress the potentially helpful high EGTs. Less EGR means the engine runs at higher combustion temps, which increases efficiency for a cleaner, hotter burn (less soot production for DPF to catch), and also consequently makes so-called "passive DPF regeneration" (DPF regeneration due to naturally high EGTs WITHOUT the use of additional fuel injection events in the exhaust stroke to artificially raise EGTs for a short period of time to regenerate the filter. The use of additional fuel injections like I mentioned above is called an "active regeneration." Passive regenerations don't need those additional fuel injection events.) happen a lot more often, which helps save your fuel economy, oil life, fuel system, CATs, DPF, turbo, etc. since less of the active regenerations are occurring. Plus, less EGR means less exhaust will be channeled into the intake, reducing the buildup of carbon in the intake manifold. Basically, less use of EGR is a VERY good thing!
But, I digress. (greatly!) Sadly, some EGR does happen in the Passat, and when it does happen that tube heats up from the hot exhaust. The insulation is there to protect its surroundings from being burned or melted.
