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Crawford or Perrin AOS, which seems better?

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needs more cowbell
95L, 07 2.5i, R6
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9,315 Posts
Discussion Starter #1 (Edited)
I'm deciding on which of these separators to get.

1-I don't want to be emptying a catch can on a regular basis and with the amount of oil I get in the intake that would be pretty regularly. Both the Perrin and Crawford let the oil drain back into the crankcase. (don't worry, the oil filter doesn't mind)

2-Both of these connect to both sides of the pcv system so they catch oil from both sides. If you get a catch can, you need to put one on each side of the system (valve cover vent side and pcv valve/crankcase vent side) to work correctly. By the time you pay for two proper catch cans you may as well get the Crawford or Perrin.

3-Both systems connect to a coolant line to heat them internally and keep water from condensing into the separated oil.


I like how both are almost maintenance free (Crawford claims theirs is zero maintenance but I don't believe) and they are one unit so they won't take up a ton of room.

The Perrin looks spiffy with its textured powder coat in black or red and the bottom easily comes off with one bolt for inspection and cleaning.

The crawford looks legit in black or aluminum but can't be disassembled for cleaning. (Top secret internals I guess :lol:)
 

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#32
95 Coupe, 95 Sedan & 95 Wagon
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12,404 Posts

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needs more cowbell
95L, 07 2.5i, R6
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9,315 Posts
Discussion Starter #3
In that case, I will be sure to read that thread also haha. I've also found a similar thread on nasioc.
 

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yep. you heard me.
03 Legacy GT wagon
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6,471 Posts
last year I did some research on the Crawford vs Grimmspeed one and it seems the crawford one is basically the best thing you can get. however its spendy. luckily i found one on ebay for $150 :)
 

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needs more cowbell
95L, 07 2.5i, R6
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9,315 Posts
Discussion Starter #5
Nice find! Of course the new perrin one is almost the same as the V2 Crawfor v2. The grimmspeed is creative but won't handle the volume of a built engine IMO. Sucks my strut brace is where the AOS will be, looks like I may have to get a different style but I prefer mine. :/
 

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Premium Member
2001 A.W. L
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13,249 Posts
I am going with the Radium catch can, it has a drain option and I like the idea of being able to monitor my blowby. I have held one in person and it is a very quality feeling piece.

Catch Cans
 

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Registered
01 RS
Joined
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25 Posts
Crawford AOS is the best on the market hands down, they have been producing the best AOS out there for awhile now. I have installed one on every Subaru I have owned and when it comes to an AOS they are the only option I will consider!
 

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Premium Member
2000,rs
Joined
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640 Posts
Depending on when you are wanting to get it I saw on FB that 3MI is working on developing an AOS, I believe in November he was getting the patent stuff worked out.
 

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Premium Member
98 OBS, Black/Grey
Joined
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2,724 Posts
I am going with the Radium catch can, it has a drain option and I like the idea of being able to monitor my blowby. I have held one in person and it is a very quality feeling piece.

Catch Cans

The machine shop I work at machined some of those catch cans for radium. They have some really cool designs and are great people to work with.
I have 2 of their catch cans waiting to go on my car.
 

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needs more cowbell
95L, 07 2.5i, R6
Joined
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9,315 Posts
Discussion Starter #11 (Edited)
I'm going with an AOS and not a catch can because I don't want to be emptying it. I work on the car enough as it is and pulling the can every few days would get annoying. I also like how an AOS drops the oil back into the engine. A catch can catches air and oil and makes a nice caramel you don't want back in the engine, an AOS drops the oil out of the air and sends it right back to the engine. My only concern with an AOS would be if I could locate it high enough so the drain hose would be able to have a downward slope. I've seen a few pics of members with crawford cans that had the milky buildup just sitting in the bottom hose but I'm willing to bet the can was below the end of the drain hose so it was just sitting at hose level. Also the newer AOS's are heated to keep water from condensing on the walls and mixing with the oil.

Also, many catch cans just aren't large enough to do the job correctly. You either get a swirl going to sling the oil to the sides which requires a good air velocity (which isn't always there) or you use the slowing of the air to allow it to drop out. The oil I'm trying to drop isn't smoke or fume oil it is mist from oil slinging of the rods and cams and blowing through the pcv system. Its clean oil mainly. A proper catch can would be pretty large, large enough so that the incoming air would slow down so much in the middle that the oil droplets would just fall out. Most catch cans are just a cylinder with two holes at the top. Some of the oil drops out but usually the two ports are right next to eachother and the air just jumps right across. I would think for one to effectively drop the oil out it would need to be at least 1.5 liter if not more, most cans are really tiny. Some of them also have baffles or screens for the oil to cling to and fall but they still miss a lot of it. The high end mishimoto has a nice design but I would prefer it about twice as large, its pretty tiny. (If I were considering a can)
 

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needs more cowbell
95L, 07 2.5i, R6
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9,315 Posts
Discussion Starter #12
This is really a tough choice considering how similar the Perrin and Crawford are. The perrin is servicable if need be which is a plus in my opinion. Doesn't mean its any better in function but its a nice feature. Wish I could find real tests comparing the two on the same vehicle.
 

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needs more cowbell
95L, 07 2.5i, R6
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9,315 Posts
Discussion Starter #14
I'd feel like a traitor buying the Perrin because its so very similar to the Crawford, but dat accessibility do
 

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needs more cowbell
95L, 07 2.5i, R6
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9,315 Posts
Discussion Starter #16
I went with the Perrin, now I just hope it allows my strut bar to stay otherwise I will have to sell it and get a different style. I also hope the Perrin can be mounted high enough that the drain oil will gravity feed back into the block. It sure won't be sucked into the can with the blowby my engine makes. :lol:
 

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needs more cowbell
95L, 07 2.5i, R6
Joined
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9,315 Posts
Discussion Starter #18
The Perrin also comes with a check valve to continue to use the pcv system to an extent where the Crawford setup caps the pcv off. You could still connect them both the same way if you got some extra fittings and a check valve but the Perrin already comes with them. Can't wait to install it, if there is still some oil residue (there is a disclaimer about built engines on Perrin's site) I will install another catch can inline with the Perrin aos outlet to see how much it is missing. If my blowby oil is mostly from pcv, the AOS should catch the majority of it, allowing me to use a generic catch can that I won't have to service frequently.
 

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IwannadrivelikeBunta
'98 RSTi, '10 LGT, '17 FXT
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3,627 Posts
Any updates on the install of the Perrin? I'm not sure on where to install; the GD mounting point looks the same as the GC, but on my 98rs, the ac dehydrator looks like it is in the way.
 
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