Ok I'll try to explain this as best as I can and the car I'm talking about is a 94 Trans Am. Anyway on the passenger side valve cover there is two "openings", one is the oil filler cap and I don't know what the other is. The other opening I'm talking about is behind the oil filler, closer to the firewall. It seems that my engine bay won't stay clean because of this. Not that I've seen it spew out oil but its always dirty on my passenger valve cover so I'm just assuming. I've looked at pics and there seems to be a hose that runs from the top part of the throttle body to this opening I'm talking about.

I'll try to get pics as soon as I can. So does anyone know exactly what this is for? Is there a part number I need to replace it? I just looked for the hose in my car and it is connected to the throttle body but the hose is cut very short and closed up with a spark plug. (I bought the car used) lol

Follow the big silver hose coming out of the throttlebody and where it goes is what I'm talking about

Same with this pic. They both go to the back of the passenger valve cover

 

That is the PCV valve (positive crankcase ventilation) It's supposed to be attached to the throttle body to create a vacuum in the crankcase and remove pressure from blowby which helps the rings to seat among other things. It should not be plugged, you need to run a new hose to the throttle body and probably need to replace the PCV valve (you can get one at any auto parts store).

 

I thought the PCV valve was on the driver side though? I followed shbox's guide to replacing that already

 

it is for the PCV system, but it is not the valve, it is the PCV fresh air tube

 

So is it necessary to have there? Will it help with gas mileage? What exactly is it for? Is it what breakmyfootoff said? Where can I buy this tube

 

You need to reconnect the hose that runs from the throttle body to the valve cover. That line supplies the filterd, MAF measured air that is pulled though the crankcase and out through the lifter valley by the vacuum from the PCV valve on the driver's side of the intake manifold.

If that line is plugged up, there is no air to help sweep blowby and other vapor out of the crankcase. It might also be a case of the PCV valve being plugged up, which means there's no place for the crankcase vapor to go, so it just blows out the grommet on the passenger side valve cover.

First replace the hose. Also put a new grommet in there so is seals well. Check the PCV valve to make sure its clean and working. Make sure the PCV valve is connected by a U-shaped hose that runs right back into a vacuum port on the drivers side of the intake. See if that solves the problem of oil blowing out of the grommet.

It should, because that allows the pressure of excessive blowby to reverse flow in the line from the TB and make the vapor flow from the valve cover, to the TB, if the PCV valve can't handle the load. In that case, you might start to see oil buildup in the top of the TB, and spillover into the intake manifold. Then you try a small Deutsch oil filter that plugs into the passenger side valve cover, in place of the small plastic elbow that connects the hose to the valve cover.

 

Thanks