Fuel in Oil Catch Can

SethRed · 11-29-2020, 04:00 PM

Decided to check my oil catch can after the first 2K miles of driving with it installed. I was horrified when I saw what appeared to be water in the can. Upon further inspection I realized it was fuel. Now, I don't no if I should be more or less horrified. What could cause this? Piston rings?

My only mods are BM3 Stage 1 and a charge pipe. I don't drive that hard, except when passing someone on the highway.

2016 328X - 57k miles on the car that I've had since April with 46k.

Thanks in advance!

sspade · 11-29-2020, 04:56 PM

Mine was the same, I dont think you need to worry about any serious issues.

Ran a catch can from approximately 35k miles to 95k miles on my last car (2014 328i) and it always had a fair amount of fuel in the can. Never had any issues with the car and would likely be still driving it it someone didnt crash into me and total it.

Was FBO w/ Bootmod3 stage 1 tune for most of those miles. Ran like a top, sure do miss it!

SethRed · 11-29-2020, 06:36 PM

Quote:

Originally Posted by sspade

Mine was the same, I dont think you need to worry about any serious issues.

Ran a catch can from approximately 35k miles to 95k miles on my last car (2014 328i) and it always had a fair amount of fuel in the can. Never had any issues with the car and would likely be still driving it it someone didnt crash into me and total it.

Was FBO w/ Bootmod3 stage 1 tune for most of those miles. Ran like a top, sure do miss it!

Thanks for the reply! The car runs great and no codes. I'll be keeping an eye on it. Hopefully nothing serious.

Billfitz · 11-29-2020, 09:37 PM

Fuel in the catch can isn't unusual, since the waste gases that leave the crankcase via the PCV are comprised of about 70% unburned fuel. Getting those gases out of the crankcase so that they won't condense there and contaminate the oil is part of the PCV system's job. When you consider how much fuel you burn in 2k miles of driving a small amount of fuel in the catch can is no biggy.

SethRed · 11-29-2020, 11:31 PM

Quote:

Originally Posted by Billfitz

Fuel in the catch can isn't unusual, since the waste gases that leave the crankcase via the PCV are comprised of about 70% unburned fuel. Getting those gases out of the crankcase so that they won't condense there and contaminate the oil is part of the PCV system's job. When you consider how much fuel you burn in 2k miles of driving a small amount of fuel in the catch can is no biggy.

The thing is, it wasn't a small amount of fuel. The can (Mishimoto) was basically full with 99% being fuel. I should have taken a picture of what was there. Will check again soon.

Billfitz · 11-30-2020, 07:19 AM

That's excessive.

SethRed · 11-30-2020, 07:26 AM

Quote:

Originally Posted by Billfitz

That's excessive.

My thoughts, exactly.

Phoenix704 · 11-30-2020, 09:10 AM

Apologies, not trying to hijack, but are there any downsides to running a catch can?

Billfitz · 11-30-2020, 10:29 AM

I'd be inclined to get a Blackstone report on the oil to be sure it's not contaminated with fuel. This could indicate bad rings.

SethRed · 11-30-2020, 10:43 AM

Quote:

Originally Posted by Billfitz

I'd be inclined to get a Blackstone report on the oil to be sure it's not contaminated with fuel. This could indicate bad rings.

Appreciate the insight. I'll check that out.

Billfitz · 11-30-2020, 11:22 AM

FWIW over 2,000 miles I'll get maybe an eighth of an inch of oil in the warmer months, a quarter inch of oil and water in the winter.

sspade · 11-30-2020, 11:32 AM

This is what my catch can looked like after 5k miles (on vehicle described above).

Looks to be mostly fuel, like OP is stating.

SethRed · 11-30-2020, 02:27 PM

Quote:

Originally Posted by Billfitz

FWIW over 2,000 miles I'll get maybe an eighth of an inch of oil in the warmer months, a quarter inch of oil and water in the winter.

Why do you think it collects water in the winter? Just from condensation? It got dramatically colder (20-30 degrees in the mornings) where I live over the past week, so perhaps that's the issue. I poured a little bit of the liquid out and tried to light it (very scientific) to no avail, so it could be water. My coolant doesn't appear low and it's not overheating. Opened the oil cap and didn't see any milkshake.

Maybe this is normal, I just didn't expect to see anything but oil in my oil catch can.

Quote:

Originally Posted by sspade

This is what my catch can looked like after 5k miles (on vehicle described above).

Looks to be mostly fuel, like OP is stating.

That's exactly what mine looks like. Just more of it over fewer miles. Perhaps it just smells like fuel because of the oiley air pumping through it all the time.

Billfitz · 11-30-2020, 03:17 PM

In winter there's a lot of water condensation in the crankcase, when the temperature is above 40 there's almost none. When the engine warms up enough to boil that water off most of it goes through the catch can, and when the can is cold it condenses there as water again. At the end of summer the oil in my can looks almost as good as the oil in my filter canister. At the end of winter it looks like sludge.

ceedawg · 11-30-2020, 04:01 PM

All you guys crack me up. Normal by products of condensation and combustion. It is totally normal to have fuel water and oil in your catch can. Some cars will hardly have anything. Ethanol is even worse. Just dump it before it gets extremely cold outside. I have two catch cans on my 600whp DSM and 1 catchcan on my F30 335.
Everyone calm down Jeez.

alohasurftoad · 11-30-2020, 04:15 PM

Quote:

Originally Posted by ceedawg

Some cars will hardly have anything

ok good. mine is bone dry. i had to check i installed the hoses properly, which they are...

SethRed · 11-30-2020, 08:24 PM

Quote:

Originally Posted by ceedawg

All you guys crack me up. Normal by products of condensation and combustion. It is totally normal to have fuel water and oil in your catch can. Some cars will hardly have anything. Ethanol is even worse. Just dump it before it gets extremely cold outside. I have two catch cans on my 600whp DSM and 1 catchcan on my F30 335.
Everyone calm down Jeez.

While I appreciate your input, the sarcastic "you are all idiots" tone was unnecessary.

Also, it's byproducts.

BrysonDM · 11-30-2020, 11:39 PM

Quote:

Originally Posted by SethRed

Quote:

Originally Posted by Billfitz

FWIW over 2,000 miles I'll get maybe an eighth of an inch of oil in the warmer months, a quarter inch of oil and water in the winter.

Why do you think it collects water in the winter? Just from condensation? It got dramatically colder (20-30 degrees in the mornings) where I live over the past week, so perhaps that's the issue. I poured a little bit of the liquid out and tried to light it (very scientific) to no avail, so it could be water. My coolant doesn't appear low and it's not overheating. Opened the oil cap and didn't see any milkshake.

Maybe this is normal, I just didn't expect to see anything but oil in my oil catch can.

Quote:

Originally Posted by sspade

This is what my catch can looked like after 5k miles (on vehicle described above).

Looks to be mostly fuel, like OP is stating.

That's exactly what mine looks like. Just more of it over fewer miles. Perhaps it just smells like fuel because of the oiley air pumping through it all the time.

If you use your stop start, it tends to build a lot of excess fuel in the oil. I live in what car manufacturers consider "extreme climate" and the dealership I work at, we constantly have fuel in the oil from people using stop start and not going for long enough drives to help burn off the excess fuel and get things up to proper operating temperature.

gzN26 · 12-01-2020, 09:10 AM

I'm curious as to why some of you all are getting that much oil/water in your OCC's...in such little time.....

Ive had my BMS OCC for over 5-10k miles and not even an 1/8th inch has accumulated.

Billfitz · 12-01-2020, 09:22 AM

Read Post #14. How often has the temperature in San Antone gone below freezing lately? In my neck of the woods it can stay below freezing 24 hours a day for weeks. That makes for a lot of condensation.

SethRed · 12-01-2020, 09:44 AM

Quote:

Originally Posted by BrysonDM

If you use your stop start, it tends to build a lot of excess fuel in the oil. I live in what car manufacturers consider "extreme climate" and the dealership I work at, we constantly have fuel in the oil from people using stop start and not going for long enough drives to help burn off the excess fuel and get things up to proper operating temperature.

That makes sense and I appreciate your insight.

DG330 · 12-07-2020, 02:20 AM

I don't have a catch can but my oil filler cap always smells of gas/fuel and it concerned the crap out of me. However, the car drives great (minus other little niggles) and I checked the oil filter and it does not smell of gas, nor the oil in the bottom of the housing, it also feels and looks like oil.

Therefore, I believe it's the crank case vapours making their way to the top of the engine to be burnt off causing the smell in the valve cover. If you're concerned you could carry out a compression test to check rings, HG and valves seating.

11-29-2020, 04:00 PM	#1
SethRed New Member 15 Rep 18 Posts Drives: 2016 328i XDrive Join Date: May 2020 Location: Northwest Arkansas iTrader: (0) Garage List 2016 BMW 328i XDrive [0.00]	Fuel in Oil Catch Can Decided to check my oil catch can after the first 2K miles of driving with it installed. I was horrified when I saw what appeared to be water in the can. Upon further inspection I realized it was fuel. Now, I don't no if I should be more or less horrified. What could cause this? Piston rings? My only mods are BM3 Stage 1 and a charge pipe. I don't drive that hard, except when passing someone on the highway. 2016 328X - 57k miles on the car that I've had since April with 46k. Thanks in advance!
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11-29-2020, 04:56 PM	#2
sspade Major General 2465 Rep 5,457 Posts Drives: F30 Join Date: Oct 2017 Location: Stevenson, WA iTrader: (3) Garage List 2016 BMW 320i [7.87] 2014 BMW 328i [6.83]	Mine was the same, I dont think you need to worry about any serious issues. Ran a catch can from approximately 35k miles to 95k miles on my last car (2014 328i) and it always had a fair amount of fuel in the can. Never had any issues with the car and would likely be still driving it it someone didnt crash into me and total it. Was FBO w/ Bootmod3 stage 1 tune for most of those miles. Ran like a top, sure do miss it!
	Appreciate 1 SethRed14.50 Quote

11-29-2020, 09:37 PM	#4
Billfitz Lieutenant General 8218 Rep 16,054 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	Fuel in the catch can isn't unusual, since the waste gases that leave the crankcase via the PCV are comprised of about 70% unburned fuel. Getting those gases out of the crankcase so that they won't condense there and contaminate the oil is part of the PCV system's job. When you consider how much fuel you burn in 2k miles of driving a small amount of fuel in the catch can is no biggy.
	Appreciate 1 SethRed14.50 Quote

11-30-2020, 07:19 AM	#6
Billfitz Lieutenant General 8218 Rep 16,054 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	That's excessive.
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11-30-2020, 09:10 AM	#8
Phoenix704 Private First Class 87 Rep 143 Posts Drives: 2014 328i Join Date: Nov 2018 Location: NC iTrader: (0)	Apologies, not trying to hijack, but are there any downsides to running a catch can?
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11-30-2020, 10:29 AM	#9
Billfitz Lieutenant General 8218 Rep 16,054 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	I'd be inclined to get a Blackstone report on the oil to be sure it's not contaminated with fuel. This could indicate bad rings.
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11-30-2020, 11:22 AM	#11
Billfitz Lieutenant General 8218 Rep 16,054 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	FWIW over 2,000 miles I'll get maybe an eighth of an inch of oil in the warmer months, a quarter inch of oil and water in the winter.
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11-30-2020, 11:32 AM	#12
sspade Major General 2465 Rep 5,457 Posts Drives: F30 Join Date: Oct 2017 Location: Stevenson, WA iTrader: (3) Garage List 2016 BMW 320i [7.87] 2014 BMW 328i [6.83]	This is what my catch can looked like after 5k miles (on vehicle described above). Looks to be mostly fuel, like OP is stating. Attached Images
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11-30-2020, 03:17 PM	#14
Billfitz Lieutenant General 8218 Rep 16,054 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	In winter there's a lot of water condensation in the crankcase, when the temperature is above 40 there's almost none. When the engine warms up enough to boil that water off most of it goes through the catch can, and when the can is cold it condenses there as water again. At the end of summer the oil in my can looks almost as good as the oil in my filter canister. At the end of winter it looks like sludge.
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11-30-2020, 04:01 PM	#15
ceedawg Major 468 Rep 1,348 Posts Drives: 2k15 335i xdrive MSport 6spd Join Date: Dec 2017 Location: Big City iTrader: (0)	All you guys crack me up. Normal by products of condensation and combustion. It is totally normal to have fuel water and oil in your catch can. Some cars will hardly have anything. Ethanol is even worse. Just dump it before it gets extremely cold outside. I have two catch cans on my 600whp DSM and 1 catchcan on my F30 335. Everyone calm down Jeez. __________________ 2k15 335i Msport xdrive 6spd Wagner Comp2 FMIC,FTP CP,stock exhaust. Fabspeed Sport catted DP, KW V2 coil overs,FBO BM3 Stg 2
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12-01-2020, 09:10 AM	#19
gzN26 Enlisted Member 17 Rep 34 Posts Drives: 328i N26 Join Date: Sep 2019 Location: San Antonio, Texas iTrader: (0)	I'm curious as to why some of you all are getting that much oil/water in your OCC's...in such little time..... Ive had my BMS OCC for over 5-10k miles and not even an 1/8th inch has accumulated. __________________ BMW 328i \| Injen Intake \| ER Charge/TIC Pipes \| VRSF FMIC and Catless DP \| BMS Oil Catch Can \| Muffler Delete \| Jb4-Map 2, 93oct \|
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12-01-2020, 09:22 AM	#20
Billfitz Lieutenant General 8218 Rep 16,054 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	Read Post #14. How often has the temperature in San Antone gone below freezing lately? In my neck of the woods it can stay below freezing 24 hours a day for weeks. That makes for a lot of condensation. Last edited by Billfitz; 12-01-2020 at 11:31 AM..
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12-07-2020, 02:20 AM	#22
DG330 First Lieutenant 70 Rep 360 Posts Drives: 330 Join Date: Nov 2018 Location: Uk iTrader: (0)	I don't have a catch can but my oil filler cap always smells of gas/fuel and it concerned the crap out of me. However, the car drives great (minus other little niggles) and I checked the oil filter and it does not smell of gas, nor the oil in the bottom of the housing, it also feels and looks like oil. Therefore, I believe it's the crank case vapours making their way to the top of the engine to be burnt off causing the smell in the valve cover. If you're concerned you could carry out a compression test to check rings, HG and valves seating.
	Appreciate 0 Quote