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2022 Crosstrek Limited
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Discussion Starter · #1 ·
Needed to pull the Crawford Baja AOS off for pending dealer visit. Found it heavier than when installed. Only 2500 miles with it on 2.5 liter Crosstrek.
Poured a 1/4 oz of thin Wood Button Circle Metal Fashion accessory
reddish looking oil from AOS. No water. Must be heavily baffled, had to rotate and twist to extract a little more several times. Flushed unit from top port with brake cleaner and then from lower port. Discolored brake cleaner is all that came out.
Engine has not used any measurable oil in 4100 miles since last oil change. Will be on 6000 OCI for next three. Plan on catching the oil to monitor color and viscosity. Plus volume.
 

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2021 Ice SIlver Sport
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My understanding was that the Crawfor AOS is maintenance free. The unit separates the oil from the recirculated PVC air and then what it catches eventually returns to the engine via the lower hose back through the PCV valve. Unlike others that have a manual valve that requires dumping from time to time. So you get the oil removed to help keep the backsides of the valves clean yet don’t have to worry about dumping the can.

From their webpage:

Not a Catch Can - Closed Loop and Maintenance Free

An AOS uses centrifugal force to force your engine’s oil through an internal labyrinth system, which makes the oil separate from engine condensation. A catch-can simply collects oil and requires one to either manually empty or pour back in the same, dirty oil. An AOS will automatically drain clean, separated oil back into your engine, without any maintenance required whatsoever. Just install and forget.
 

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Discussion Starter · #3 ·
You are correct, it is designed to be maintenance free. Does not come apart to drain.
I am pulling it before dealer oil changes. Do not want to chance any hassles about warranty. Took 25 minutes to remove and reinstall the original pipe. I have the intake down to a couple minutes on or off.
Glad to see it is catching oil. That little bit in the cup may not be all it filtered out. Both hoses had almost no oil film, so not much oil traveled through in 2500 highway miles.
 

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Discussion Starter · #5 ·
My limited understanding oil is pulled back into crankcase when the air in crankcase cools. The volumes are very low. And the process happens every time the engine cools down. Not like a catch can where the liquid is caught and dumped periodically.
Catch cans act as a trap with inlet and outlet at the top of the can. Liquids drop out. The liquid is usually 90% water. And at 2500 miles normally a couple ounces of fluid with a thick oil film on top.
Checked the dark fluid in AOS and it was oil. Nothing separates out. Assume the AOS is hotter and the water boils off. I put 900 miles on car Wednesday. It stayed hot under the hood for more than 15 hours. Might explain why catch cans catch mostly water and this time the AOS had all oil.
 

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Needed to pull the Crawford Baja AOS off for pending dealer visit. Found it heavier than when installed. Only 2500 miles with it on 2.5 liter Crosstrek.
Poured a 1/4 oz of thin View attachment 312935 reddish looking oil from AOS. No water. Must be heavily baffled, had to rotate and twist to extract a little more several times. Flushed unit from top port with brake cleaner and then from lower port. Discolored brake cleaner is all that came out.
Engine has not used any measurable oil in 4100 miles since last oil change. Will be on 6000 OCI for next three. Plan on catching the oil to monitor color and viscosity. Plus volume.
Are you seldom revving your engine beyond 4k rpm?
 

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Discussion Starter · #7 ·
Yes, car seldom revs to 3,000 rpm. Purchased car for long highway trips.
In the long drive from Houston to Nashville the highest I saw was around 2300 rpm. That was climbing a grade at 75 mph. Around here it is 1800 rpm at 75.
The CVT works as promised. Reduces oil slinging.
 

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Yes, car seldom revs to 3,000 rpm. Purchased car for long highway trips.
In the long drive from Houston to Nashville the highest I saw was around 2300 rpm. That was climbing a grade at 75 mph. Around here it is 1800 rpm at 75.
The CVT works as promised. Reduces oil slinging.
Yep, so it confirms my observation that the problem with Crosstrek PCV is on high rpm, I can smell oil burning when accelerate until redline and slow down. With AOS it reduce the smell, but still happen.When I rev often, my AOS contains about half cup of oil. However recently when I drive leisurely, I can tell the carbon deposit does not accumulate that fast and the engine maintain the quiet note of the engine.
 
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