Brown liquid in catch can

Carlosskrr · 07-04-2020, 09:05 AM

I took off my catch can off today and noticed that the liquid was brown this is the first time I have taken the catch can off after driving for a while is this normal ? I always thought the liquid the catch can caught was just supposed to look like black oil
2015 428i n20

Billfitz · 07-04-2020, 09:28 AM

That's not unusual. The can catches oil and water vapor, which when mixed can look like that. The good news is that it got caught by the can instead of going through the PCV.

paimon.soror · 07-04-2020, 01:33 PM

Yup, also known as "milkshake". Happens if you take short trips and the car doesn't get up to temp. As mentioned above, excess water vapor

BMW DIY Guy · 07-04-2020, 01:44 PM

The liquid in my N55 catch can looks like oily water.. sorta.. with floaties and smells like death turpentine. Just NASTY.

chowser51 · 07-04-2020, 01:51 PM

How often do you guys check your oil catch can?

I only installed it about 3000 miles ago.

BMW DIY Guy · 07-04-2020, 01:54 PM

Every oil change.. the can is about half full by then.

Billfitz · 07-04-2020, 02:09 PM

I only drive some 4,000 miles a year, 3,000 of that between April and November. I never have any significant accumulation in the fall, but come spring I have a fair amount of oil/water sludge in the can. Short trips in cold weather are hardest on the engine and battery.

B58 parts · 07-04-2020, 02:29 PM

Since changing to the 5w40 I barely get anything in the can. There's a residue or film but no liquid, when I first installed the can and with the 0w20 I'd get a tiny bit of oil/water/fuel mix.

Not sure if it's better or worse just saying.

The b58 does seem to like the thicker oil and the ngk 94201 for sure.

07-04-2020, 09:05 AM	#1
Carlosskrr Private First Class 33 Rep 144 Posts Drives: Bmw f36 Join Date: Oct 2019 Location: Florida iTrader: (1)	I took off my catch can off today and noticed that the liquid was brown this is the first time I have taken the catch can off after driving for a while is this normal ? I always thought the liquid the catch can caught was just supposed to look like black oil 2015 428i n20 Attached Images
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07-04-2020, 09:28 AM	#2
Billfitz Lieutenant General 8243 Rep 16,083 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	That's not unusual. The can catches oil and water vapor, which when mixed can look like that. The good news is that it got caught by the can instead of going through the PCV.
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07-04-2020, 01:33 PM	#3
paimon.soror Captain 629 Rep 965 Posts Drives: 2016 F36 435x MSport Join Date: Oct 2017 Location: Hartford, CT iTrader: (3) Garage List 2016 BMW 435xi GC [6.00]	Yup, also known as "milkshake". Happens if you take short trips and the car doesn't get up to temp. As mentioned above, excess water vapor
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07-04-2020, 01:44 PM	#4
BMW DIY Guy Brigadier General 3075 Rep 3,022 Posts Drives: 2019 M2 Competition Join Date: Jan 2017 Location: Maple Valley WA iTrader: (1) Garage List 2024 BMW M2 [9.80] 2017 BMW X1 [10.00] 2001 BMW X5 [10.00]	The liquid in my N55 catch can looks like oily water.. sorta.. with floaties and smells like death turpentine. Just NASTY. __________________ Check out my BMW DIY Channel on YouTube! E, F and G series projects from Active Autowerke, Bimmertech, Kies Motorsports, AvinUSA, Karbonius Composites and more! YouTube BMW DIY Guy 'Nimona' G87 M2 Build Thread 'Lillith' F87 M2 Competition Build Thread
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07-04-2020, 01:51 PM	#5
chowser51 Colonel 2025 Rep 2,805 Posts Drives: F33 430 and F39 M35i Join Date: Feb 2009 Location: Cleveland, OH iTrader: (3) Garage List 2018 BMW 430i xDrive [0.00]	How often do you guys check your oil catch can? I only installed it about 3000 miles ago.
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07-04-2020, 01:54 PM	#6
BMW DIY Guy Brigadier General 3075 Rep 3,022 Posts Drives: 2019 M2 Competition Join Date: Jan 2017 Location: Maple Valley WA iTrader: (1) Garage List 2024 BMW M2 [9.80] 2017 BMW X1 [10.00] 2001 BMW X5 [10.00]	Every oil change.. the can is about half full by then. __________________ Check out my BMW DIY Channel on YouTube! E, F and G series projects from Active Autowerke, Bimmertech, Kies Motorsports, AvinUSA, Karbonius Composites and more! YouTube BMW DIY Guy 'Nimona' G87 M2 Build Thread 'Lillith' F87 M2 Competition Build Thread
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07-04-2020, 02:09 PM	#7
Billfitz Lieutenant General 8243 Rep 16,083 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	I only drive some 4,000 miles a year, 3,000 of that between April and November. I never have any significant accumulation in the fall, but come spring I have a fair amount of oil/water sludge in the can. Short trips in cold weather are hardest on the engine and battery.
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07-04-2020, 02:29 PM	#8
B58 parts Captain 477 Rep 797 Posts Drives: '17 340ix 6MT Join Date: Nov 2017 Location: US iTrader: (0)	Since changing to the 5w40 I barely get anything in the can. There's a residue or film but no liquid, when I first installed the can and with the 0w20 I'd get a tiny bit of oil/water/fuel mix. Not sure if it's better or worse just saying. The b58 does seem to like the thicker oil and the ngk 94201 for sure.
	Appreciate 2 Carlosskrr32.50 alohasurftoad3079.50 Quote