Real cause of the smoking issue with our cars??
 

2008.5 with 18,000 miles. Put in a testpipe and a SRI about 3,000 miles ago. Absolutely no problem until a week ago. Like others, my car started to smoke after idling for 2-3 minutes. I decided to put the stock second cat back on and the smoking stopped. I thought I had overfilled the oil by just a bit thus causing the smoking. Yesterday, I decided to change the oil all together and re-installed the testpipe. Yes, it smoked again. I put the second cat back in this morning and indeed the smoking stopped.

Now, is it because of the additional back pressure from the second cat preventing the oil from leaking thus preventing smoking or is it because the second cat. neutralized the smoke so it does not show coming out of the tailpipe?

I think I am just going to drive the car without the testpipe. If the car smokes, I will just have Mazda take care of it under warranty.

well there are people who are bone stock that smoked too - including cx-7's...

I can not imagine the second cat has the ability to eliminate the smoke. The smoke from burning oil has to go somewhere.

Mine smoked bone stock, with the second cat. So did a buddy's.

/thread

The second cat just hides it. Let it idle 8-10 minutes and it'll smoke again, same thing happened with my car. Got my turbo replaced under warranty.

when my MS6 was bone stock it smoked when idling for too long, mods didnt change this, including a tp and cbe... put 5w40 rotella in, smoking stopped. When the rotella gets in the 2500-4000 mile area SOMETIMES it will smoke if I leave the car idling for more than 10 min, but usually I never see smoke anymore.

The way it has been described to me, it is that the pressure differential between the oil pressure and the turbine housing is too great and the seal gets pushed out and oil leaks. With the cat, there is slightly more pressure in the turbine housing and it is more difficult for the oil to seep past the seal.

Cats dont eliminate oil, they actually get ruined by oil.

switch to 5w40 and change often - no smoke for me

The problem is still there even with all the band-aid fixes. My concern is will the cat suffer a premature death due to the excess oil leaking. This is a potential long term problem for those of us living in states that require smoke checks. I guess I just have to see if Mazda will do something about this issue.

JL

Just go into your local mazdaspeed dealer and get it checked out. Let it sit there and idle outside of their place until it starts smoking again. If you're still under warranty bam! new turbo. As a side note, tell them you have already changed the oil to 5w-40 as well and that did nothing because they will tell you to do that first.