WHAT THE? I just found a foamy white lotion gunk coating my oil filler neck!
 

I just went to cap off my oil with a half a quart when I found some nasty white foamy lotion type stuff all over the inside off my engine oil filler neck. There was also some clear liquid dew on the lotion. I couldn't tell if it was water or fuel. Also, my oil cooler was just flow tested, Ihave new ( slightly used) ss oil lines, and oil was just changed. Does anyone have a clue as to what the heck this stuff is?!
Thanks,
Damon

It's water vapor inside the engine that has condensed inside the cool(relatively speaking) oil filler tube. The TII oil filler tubes seem to collect more since they are longer and the opening is further away from the engine. What did they use to flow test the oil cooler? It may have had some residual water in it.

Is it ok to run my car? does a bad seal cause water vapor in the engine or does it just occur naturally?

They used pressurized water to test the oil cooler.

probably just some water that didn't get out after the testing. just wipe it out of the filler and monitor it.

this is very common on rx8's and mazda says exactly what he just said,but they said it doesn't hurt anything/ just change your oil if it bothers you

Thanks guys! now I'm not freaked out to start it up.

It's pretty safe to say that if u blew ur engine...u'd probably know it. In most cases anyway :)

In all probability it's residual water from your oil cooler flush. If you want to stay on the safe side, go ahead and change your oil and filter again now.

Yeah the 8s are notorios for it, they even came up with a new dipstick or tube for it. Haven't had it happen on either of my 7s yet but I have seen it on 3 8's. Run the piss out of the car or change the oil...should go away.

With the rx8 it's only because Mazda didn't put in a PCV system. The oil filler neck is just hooked straight to the intake and it doesn't work very well, plus some people get a fair amount of oil traveling into the intake a pooling. The solution is just to put on a catch can in between, no foam and no oil in the intake.

As for this issue, it probably was just the pressure test like everyone else has been saying. Clean it off every time you check your oil, or change your oil/filter earlier than normal for a while. Eventually it will go away if it truly was just from the pressure test. If it wasn't and your PCV system is not functioning correctly, you'll either have to fix it or install a catch can and route it properly to capture the vapor.