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IAG Comp AOS Fuming

1136 Views 8 Replies 3 Participants Last post by  cerberus_oz, 
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A couple years ago I purchased an IAG competition (vent to atmosphere) AOS. Ever since, it has progressively vented more visible vapors underneath the car.

I get how the system works, and am ok with the concept, and the associated smell and vapor, but now it seems to be burning more oil, and visibly vaporizing in the heat of the summer. Kinda embarrassing to be honest. It's almost like the swirl pot doesn't work, or is ineffective anymore. I'm losing about 1/2 qt per 2500 OCI with clean wear metal wear on my Blackstone reports. Anybody experience this, or have a solution?

I'm worried that my oil temps are higher than they should be, or my very nice, high dollar AOS is not working.

Being an 09 MY, my car was not equipped with an oil cooler. Should I consider installing one?

Planning on some heat management modifications, and curious if header wrap insulates as well as it shields if that makes sense?

I've also noticed that there aren't any/many oils in 5w40 with an SN plus (vaporization resistance) rating. This is the weight recommended by IAG for my block. Any thoughts here?

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Find out how much it would cost to get oil temp monitored before you go and put a cooler on it.

Coolers arent of huge benefit unless you are absolutely hammering on the car - the stock 'cooler' on the wrx is more of a heat-exchanger with the water coolant system - intended to get oil up to temp quicker moreso than to take heat out of the oil.

Dont throw money at problems when you dont know what the causes are - or youll be chasing problems without understanding why forever.

Are you running a PCV with that AOS?
If so - a stuck PCV may cause similar behavior....find out the cause, before applying fixes.
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Not running pcv.

I was looking more to a cooler which the oil runs through, not bringing coolant to the oil.

I agree that throwing money at parts isn't the way to go, and will likely start with oil temp gauge. Wanted to do this anyway.

Causation is what I was hoping to find some insight on....

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Looked at AMSOIL?
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Makingforestergreatagain said:
Looked at AMSOIL?
Click to expand...
Yeah, didn't see an sn+ 5w40

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skirbykat said:
..
aren't many SYNTHETIC oils in 5w40 with an SN plus (vaporization resistance) rating.
Click to expand...
fixed it for you.
Amsoil Signature Series has low volatility and in the weight you want.
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My understanding of the sn+ rating has to do with LSPI,,,low speed precognition, ,,

Volitility(evaporation) isn't that something else entirely?
Amsoil has plenty of sn+ rated oils.

After checking, you are correct, no 5w 40, but there is a 0w40 sn+,,,first number is the viscosity cold, of course.
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Makingforestergreatagain said:
My understanding of the sn+ rating has to do with LSPI,,,low speed precognition, ,,

Volitility(evaporation) isn't that something else entirely?
Amsoil has plenty of sn+ rated oils.
Click to expand...
My understanding (not to be redundant in phrasing) is that LSPI is primarily caused by oil droplets returning through the intake tract via pcv, so an oil that is rated to stave off LSPI should vaporize off less.

Either way, I don't really want to stray from IAG's recommended oil weight for my short block, so 5/40 is where I'm comfortable. I think a bit of header wrap on the downpipe and gold reflective tape on the AOS is in order, maybe even sleeve the lines going to and from the AOS to help, but temp monitoring first so I can see results with data.

Thanks for the feedback and thoughts so far, open to more thoughts and opinions..........


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skirbykat said:
My understanding (not to be redundant in phrasing) is that LSPI is primarily caused by oil droplets returning through the intake tract via pcv, so an oil that is rated to stave off LSPI should vaporize off less.

Either way, I don't really want to stray from IAG's recommended oil weight for my short block, so 5/40 is where I'm comfortable. I think a bit of header wrap on the downpipe and gold reflective tape on the AOS is in order, maybe even sleeve the lines going to and from the AOS to help, but temp monitoring first so I can see results with data.

Thanks for the feedback and thoughts so far, open to more thoughts and opinions..........


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Click to expand...
Another thought;

If your oil pump bypass is opening, or is stuck open....youll notice this as low oil-pressure if measured from one of the galleries near the top of the block.

This can also cause the oil to get way hotter, if the bypass is open.

Many things could cause this kind of failure mode;
1) Poorly machined oil pump pressure relief cylinder / piston, fouling and stuck when opened last
2) debris causing pressure relief to get stuck open
3) debris partially blocking an oil passage in the engine, causing higher pressure / lower flow (and creating pressure-releif to stay open, thus heating the oil up).
4) Maybe the oil pickup isnt sucking enough volume due to a cracked brazing joint - causing /low/ pressure and hotter rotating parts (thus, heating the oil)???


You'd want to get the oil temp and pressure checked before really worrying about any of those....but they are a few things that could contribute to hotter than usual oil.

How many ways do we want to scare you with potential causes for unknown oiling issues? :p
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