When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Ages ago I read a thread where they said catch cans weren't anything complicated and even a coke can would do lol. Is a more expensive catch can really that much better or are they all the same.
Looking at the few return to sump kits there only seems to be some sort of baffle where is it keeping the oil or is it plumbed in to get the oil from blow by and put that back in the sump. I've started looking into this again and I'm getting more and more confused.
Ages ago I read a thread where they said catch cans weren't anything complicated and even a coke can would do lol. Is a more expensive catch can really that much better or are they all the same.
Looking at the few return to sump kits there only seems to be some sort of baffle where is it keeping the oil or is it plumbed in to get the oil from blow by and put that back in the sump. I've started looking into this again and I'm getting more and more confused.
Ideally you want an AOS with a decent baffle so that the oil mist is caught out of suspension and then returned to sump. These cars can breathe heavily, particularly on track days where high cornering speeds are involved. The most ideal setup would involve venting the AOS to atmosphere as, even with a large percentage of the oil being “caught”, some will invariably still work it’s way through to the inlet and the gasses coming out of the crankcase aren’t exactly rich in oxygen either.
Ideally you want an AOS with a decent baffle so that the oil mist is caught out of suspension and then returned to sump. These cars can breathe heavily, particularly on track days where high cornering speeds are involved. The most ideal setup would involve venting the AOS to atmosphere as, even with a large percentage of the oil being “caught”, some will invariably still work it’s way through to the inlet and the gasses coming out of the crankcase aren’t exactly rich in oxygen either.
Hi mate, hows it going, hope you're doing well.
So from the research I've done and my limited understanding if a catch can is plumbed back into sump that makes it an AOS or are both terms interchangeable. Another question do you want the oil from a catch can going back into the sump because doesn't it get loads of condensation. Or is it a case of when its plumbed in to the sump that gunk doesn't get in.
the 'gunk' only forms because of condensation and isn't actually there under correct operating conditions as the gas is too hot and the moisture simply burns off...
once everything cools you can get 'gunk' forming in the colder can
the 'gunk' only forms because of condensation and isn't actually there under correct operating conditions as the gas is too hot and the moisture simply burns off...
once everything cools you can get 'gunk' forming in the colder can
So follow up question, is that gunk safe to go back into the oil pan. And secondly if it is plumbed to sump I'm assuming there would be no oil for it to turn into gunk at all. The job of the catch can is to catch blow by and not filter the oil. Thats the job of the oil filter.
So from the research I've done and my limited understanding if a catch can is plumbed back into sump that makes it an AOS or are both terms interchangeable. Another question do you want the oil from a catch can going back into the sump because doesn't it get loads of condensation. Or is it a case of when its plumbed in to the sump that gunk doesn't get in.
Thanks
All good thanks buddy, I hope you are too? The term AOS is generally used for a device that returns to sump, whereas a catch can just catches it. The problem with a catch can is they need emptying whereas an AOS is fit-and-forget.
As Alyn has said, the condensation/oil mixture isn’t an issue. Some AOS’s like the Perrin and IAG use coolant to pre-heat the outer jacket of the AOS to stop condensation from forming, but it’ll still happen in any pipework that is cooler than the blowby gasses. If you were to take a standard breather hose and cut it open, you’d see it in there too. Once the oil from the AOS reaches the hot oil in the sump the condensation burns off again and you are left with clean oil. Once you do your first oil change you will see there’s nothing to worry about.
All good thanks buddy, I hope you are too? The term AOS is generally used for a device that returns to sump, whereas a catch can just catches it. The problem with a catch can is they need emptying whereas an AOS is fit-and-forget.
As Alyn has said, the condensation/oil mixture isn’t an issue. Some AOS’s like the Perrin and IAG use coolant to pre-heat the outer jacket of the AOS to stop condensation from forming, but it’ll still happen in any pipework that is cooler than the blowby gasses. If you were to take a standard breather hose and cut it open, you’d see it in there too. Once the oil from the AOS reaches the hot oil in the sump the condensation burns off again and you are left with clean oil. Once you do your first oil change you will see there’s nothing to worry about.
That's helped a lot Danjo, thanks for the info. So out of what's currently available out there, and an AOS is probably a better option as it's an install and forget about system what would you say would be the best buy as i want to fit one within the next couple of weeks to fit in with my full service.
Yes it will, I’ve fitted a few of these now to different cars, including the 08’s. The “fitting” side of things simply involves two self tappers into the chassis rail so it’s easy enough to find a suitable position on any car. Also simple enough to knock up a bracket if you wanted to mount it elsewhere. The only thing you need to make sure is that it’s high enough that the drain is downhill.
That's helped a lot Danjo, thanks for the info. So out of what's currently available out there, and an AOS is probably a better option as it's an install and forget about system what would you say would be the best buy as i want to fit one within the next couple of weeks to fit in with my full service.
The best all rounder when you take into account the cost, ease of fitment would be the RCM by some margin. The IAG and Perrin units are good (I have the Perrin) but are difficult to mount without fabricating a bracket as they are designed for left hand drive cars. That being said, they are simple to mount if you have a FMIC as both companies offer a pitch stop bracket, which is what I use on mine. I would have no problem using either of the RCM’s though.
All good thanks buddy, I hope you are too? The term AOS is generally used for a device that returns to sump, whereas a catch can just catches it. The problem with a catch can is they need emptying whereas an AOS is fit-and-forget.
As Alyn has said, the condensation/oil mixture isn’t an issue. Some AOS’s like the Perrin and IAG use coolant to pre-heat the outer jacket of the AOS to stop condensation from forming, but it’ll still happen in any pipework that is cooler than the blowby gasses. If you were to take a standard breather hose and cut it open, you’d see it in there too. Once the oil from the AOS reaches the hot oil in the sump the condensation burns off again and you are left with clean oil. Once you do your first oil change you will see there’s nothing to worry about.
Getting there mate, need to get started on the car again, its been sat far too long.
Thanks guys for the detailed explanations. Any thoughts on the link I put up.
Banjo, i'll see what Simon at Chevron motorsport recommends, your recommendation on the RCM one does seem a sensible one and it seems like a good piece of kit and a good starting point, i could get either the IAG or Perrin one but i'll go with other peoples advice, like yours and to see what Chevron say.
Hedge, is it for sale, if it is how much do you want for it and do you have a pic or link to the exact one you have.
It's for sale, but it's for the tmic, not the fmic. I believe it's the same, but the hoses are shorter, but as it's designed for lhd, you need to buy extra hose any way.
I'm getting rid because the Sti flexi strut bar makes it much harder to fit, height wise.
It's for sale, but it's for the tmic, not the fmic. I believe it's the same, but the hoses are shorter, but as it's designed for lhd, you need to buy extra hose any way.
I'm getting rid because the Sti flexi strut bar makes it much harder to fit, height wise.
What colour tank is it and is it unused and boxed with everything that came with it, how much do you want for it ? PM me a couple of pics if poss as long as it aint red as im trying to remove all the red out of my engine bay that the previous owner put in lol
What colour tank is it and is it unused and boxed with everything that came with it, how much do you want for it ? PM me a couple of pics if poss as long as it aint red as im trying to remove all the red out of my engine bay that the previous owner put in lol
Can't seem to find anyone that used it and also post a review / photos of the this installed.
I really like the idea that it is specifically made for the GC8 and assume I won't have to tackle the hassle of finding a location to mount the reservoir or drill new holes into the car.
The only problem i see with that one is it doesn't have a drain plug like a lot of the competition do, to clean it or remove any excess oil you'd have to completely take the tank off the car.
Can't seem to find anyone that used it and also post a review / photos of the this installed.
I really like the idea that it is specifically made for the GC8 and assume I won't have to tackle the hassle of finding a location to mount the reservoir or drill new holes into the car.
I have this fitted to my car, fits perfectly on the chassis rail without interfering with the AC system or fuel filter. Didn't run mine back to the sump, but it's getting changed over winter. Seem to remember I had to put a couple of rivnuts in to hold it?
This year I've done tracktime at Spa, Nurburgring GP and twelve laps of the Nurburgring. In all that time it's only collected maybe a third of a cup of oil. It's not bypassing the can as I put a filter on the output pipe under the car. I don't run back to the inlet.
Results might be skewed slightly as it's not the original V6 engine, it's now running a V8 avcs engine and I don't know if Subaru improved oiling issues between the generations.
Supplied by AS Performance. Anything else you want to know?
I have this fitted to my car, fits perfectly on the chassis rail without interfering with the AC system or fuel filter. Didn't run mine back to the sump, but it's getting changed over winter. Seem to remember I had to put a couple of rivnuts in to hold it?
This year I've done tracktime at Spa, Nurburgring GP and twelve laps of the Nurburgring. In all that time it's only collected maybe a third of a cup of oil. It's not bypassing the can as I put a filter on the output pipe under the car. I don't run back to the inlet.
Results might be skewed slightly as it's not the original V6 engine, it's now running a V8 avcs engine and I don't know if Subaru improved oiling issues between the generations.
Supplied by AS Performance. Anything else you want to know?
Thank you very much, appreciate the feedback. Now I am pretty sure this will be the next thing I purchase for my car.
Would you happen to have a photo of it installed? Curious to see where it is actually located.
Thank you very much, appreciate the feedback. Now I am pretty sure this will be the next thing I purchase for my car.
Would you happen to have a photo of it installed? Curious to see where it is actually located.
I can get you a picture of mine if you want but once they are fitted and everything is back in the engine bay they almost disappear. When I first enquired with RCM they sent me this picture which shows fitment pretty well, you can see it under/around the aircon drier at the back right of the engine bay.
I can get you a picture of mine if you want but once they are fitted and everything is back in the engine bay they almost disappear. When I first enquired with RCM they sent me this picture which shows fitment pretty well, you can see it under/around the aircon drier at the back right of the engine bay.
Ahhh yes, I see! Very clean looking and discrete, thank you I'm sold.
Never occurred to me to ask RCM themselves for a photo of their product.
Recently got a bottom end rebuild done....as part of it I went from AOS setup to RCM return to sump setup, obviously made easier by having a front mount fitted. Mounted via bracket on pitch stop mount, under brace
Ill also have this setup for sale after xmas as it's now off the car, worked perfectly across 2 of my stis over 7yrs, just went with RCM setup as engine was out of car so was rude not to
02 December 2021, 06:01 PM
