Rough idle and low power problems.. (also using 5w-30)
 

So Friday coming home from work I noticed the engine having some pretty bad power issues especially from stop. At idle, it feels as if it was dying. The gas was pretty low so I filled it up and it returned to normal on the way home.

This morning I go to drop something off, a quick 3 mile trip. Everything was normal. When I started the car again, I was having the same issues + flashing CEL, and took it down to the dealership. After a while they told me it was running on 1 rotor and they tried replacing the spark plugs to no avail. The tech's work day ended today and they are going to finish up the tests on Monday, including compression tests.

What could be wrong and what kind of repairs am I looking at?

One of my main concerns is that I switched over to Castrol GTX 5w-30. I'm not sure what to tell the tech should I have a major engine issues. Any recommendations would be greatly appreciated.

The car is a 2004 RX-8 with 47300 miles. Oil change was performed at 44600 miles switching over to 5w-30 from whatever was in the car before (bought it used from a different dealership)

Sounds like you might be getting a new motor, but I can guarantee that 5w30 had NOTHING to do with it.

The best oil lab available would not be able to discern the difference between samples of used 5w30 oil and used 5w20.

S

Should I just tell them that I've been using 5w-20 castrol gtx then?

Man.. this really sucks, I am starting school in a 2 weeks and I am supposed to move out from SC to MI tomorrow....

Not quite sure how I'll move my stuff to Michigan from here in SC.... and my apt. lease is ending monday...

Hm, will they likely try to check if I used 5w-30?

you'll be fine
5w30 > 5w20. stupid EPA:rant:

So using 5W-30 won't void my warranty then? I should just tell em I used 5W-30 if they ask? I assumed it wouldn't, but I hadn't really thought of the case of them pulling out my engine... In fact, I switched over in order to prevent it...

Thanks for all your responses.

They MAY want proof of timely oil & filter changes if there is a lot of mileage on it, but they don't usually ask/care about brand or viscosity.

S

Sounds like you might be in line for a new motor. Don't worry about the oil. Many others on this forum have had motors replaced and had more issues thatn what viscosity of oil they were using.

You should be fine. You might have bad coils.

If your compression is ok then you may have problems with the coils or it is the fuel pump.

Let's hope it's those and not the engine. Being stuck here without a place to live is really getting old fast....

Thanks for the great info guys. It's been really reassuring.

Well just finished driving it from SC to MI. It was just some bad coils and spark plugs! Phew!

Thanks guys

looks kike in the same boat with u but im having a fluttering sound at around 4200 rpm and a loss of power sorry to hear bout this man hope all goes well