Quote:
Originally Posted by 911monty
Totally agree. However, while motor oil may kill the cats, the only way to know will be to run them and cook the oil out with exhaust heat. I don't know the condition of the exhaust manifold to head bolts, but at this point I wouldn't risk breaking a few just to see if there is oil in there when we all know the answer to that one (see post 38). If the cats fail deal with it then. They may be fine. Lots of failed AOS that oil soaked cats came back from.
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The US SE has 4 cats. 2 in the headers and 2 before the muffler. One problem i see is back pressure. Oil / water mixture in cats can be very tough / doughy (don't know the right english word). If you want to start the car, this can cause more problems than a sheared off head bolt. Also if the oil starts to burn (specially the header cats) by exhaust temperature, the cats will clog / die in a short time.
There are specialized companies that can clean oil contaminated catalytic converters. Oil contamination happens often if turbochargers fail.
And yes, if one or more header bolt shears off this is also a problem. But if you soak them in rust dessolver (min. 2-3 days and don't start the engine in this time) and clean them extensively (best is to soak and clean more than one time) with a steel brush before you try to open them in general they don't shear off. In my opinion these shear off fails are often caused by much too short preparation time.
My approach is always to check for risks and try to go the way with the least risks. Even if it takes more time. And for shure everybody has made it's own experiences and has it's own opinion. In the end everything can go wrong, even if you have tried to take all aspects in consideration.
Just my 2 cents…
Regards, Markus