Oil catch can opinions

[AZjeff]

Originally Posted By: Trav

Using an oil that doesn't go up in smoke like your mothers frying pan oil will probably eliminate much of the problem they are trying to fix with these things.


This is my ultimate plan, can or no can. Low NOACK 10w-30 will be going in after warranty at the latest. Might try a run of it soon just to see if there's any difference in what I catch.

 

[parshisa]

I have installed a can on my Turbo Civic around 700miles ago and guess what: it is empty!!!! Absolutely nothing in it. Either it doesn't work or I have 0 blowby. To be fair, I do mostly highway.

 

[deanm11]

I checked the can (Bob's catch can, supposed to be a good one) I put on my Challenger 6.4 on the dealer's lot after about 2000 miles. Didn't drain/catch a drop of oil. I took it off. On my '08 Vette 6.2, I would capture a modest amount of oil and some would get past, as I had the intake off and saw it in the intake runners. I don't know that I'll ever have the Hemi apart to know whether oil is getting in there or not.

 

[SHOZ]

I've used catch can on Naturally Aspirated and Forced Induction cars. On my Taurus SHO V8 (NA) it had one dry intake valve. The other got the spray from the fuel injector. The dry valve would coke up and some have had the valve stick and crash into the piston because of it.

I had a catch can between the PCV and the intake on the NA engine. And I sealed off the other side where the crankcase vent hose was. This developed about 5-7" Hg of vacuum on the crankcase when the intake was in normal vacuum. The catch can also had a vacuum check valve that was closed when there was vacuum. But at WOT or when the engine was shut off it opened and dumped the can. Worked great.

On my turbo car I have a catch can on both sides. The PCV side collects the most but when in boost the PCV is a check valve so the blowby pressurizes the crankcase a bit and pushes oil mist out the valve cover into the pre turbo intake. Very little is actually collected over 5k miles but it is almost all pure oil.

On the PCV side what is collected is not oil but combustion byproducts. It is a yellowish stinky mix and will evaporate leaving no stain if dumped on the cement and left for a couple of days.

From my turbo car with two catch cans the first pic shows the oil on top collected from the pre turbo intake side can. The second one shows what was collected from the PCV side can. You can see they are not the same substance. Both catch cans are out of the engine bay for a cooler location and lower that the originating hose.

Here's a pic of the NA catch can dumping the stuff from the can when the engine was off and the temperature was just below freezing. Beware that they can freeze up and if yours is plumbed is in such a way it may block the PCV flow.

 

[Trav]

Just a thought for you guys to consider. I use a breathing system right off my air compressor, its not an old compressor but a large newer Quincy with no noticeable blowby but it does have a slight amount because the water that drains out has a slight oily feeling.

Using a air compressor as a breathing source can be deadly unless very specific filters are used and maintained properly then its quite safe. The biggest problems are carbon monoxide and oil vapor (making old worn out units a no no), a catch can will not remove or prevent the hot oil vapor (smoke)from getting to the filters and that's the point.

It takes a 40 micron water/particle filter with a 5 micron particle filter then to remove the oil vapor a coalescing filter followed by a dryer and carbon filters.
The large coalescing filter does the heavy lifting removing the hot oil vapor.
Pulling the oil vapor though a can isn't doing much of anything except catching whatever vapors are condensed after shut down in the line, the question is how much got past it when the engine was running? The answer is almost all of it. So for the couple of teaspoons it caught half a pint may have gone past it.

Over the years I have looked at a lot of these things, some of them at least uses some screens in an attempt to remove oil droplets from the vapor but its no where near as effective as a true coalescing filter, others are just an empty can.
If your thinking why not just use a coalescing filter in the line, you could but it wont last long and the elements are costly. IMO there are only 2 reasons for oil getting into the intake runners, either the PCV system is poorly designed like on some old car with the PCV valve stuck right in the non baffled valve cover where it picks up slash or the running oil with high volatility.

Today's modern engines especially with turbo;s can get the oil very hot, keeping the oil temps down by using a thermostatically controlled oil cooler and less volatile oil would go a lot further in preventing the hot oil vapors from forming in the first place rather than trying to catch them after the fact.

 

[WhizkidTN]

FWIW: Yesterday I changed my oil (OCI of 4K miles) on my Turbo Optima and drained about 1~1.5oz of liquid gunk out of my PCV side OCC. Doing it's job from what I can tell.

 

[PeterPolyol]

Good show kid, yeah it's some nasty stuff. Corrosively acidic water and oil sludge emulsion are just gross.

 

[mlatour]

2014 Ford F150XL here with the 3.7 naturally aspirated V6 base engine,
truck I purchased brand new on which I installed a catch can within the first month of ownership.
(generic catch can in which I added mesh and a longer tube to better separate vapors)

Truck is not babied nor beaten, 25% city / 75 highway driven,
no matter the ambiant temperature I always warm up the drivetrain gradually.
Under light to moderate loads, typical engine rpms are between 1800-2500.
(very torquey for a V6 with a 6-speed auto / 3.73 gears)

Tows / hauls on occasion at most 1500-2000lbs (dirtbike, building material etc.)
at no more than the posted speed limit of 100km/h (62 MPH)

Oil specs are for 5W-20 (which I use in winter) but commonly use 5W-30
Original fill was dumped at 1000 miles, have always used Pennzoil Platinum since.

No matter the mileage I've changed the oil twice a year since new, spring / fall.
The average of the intervals are likely in the 4000 miles range.

Each time I've also drained about one+ ounces of oil from the catch can,
that's oil that would have otherwise been sent in the intake stream.

I don't mind doing that simple task which takes 25 seconds at most,
IMO there is no downside, the plusses are preventing contamination of sensors
(which would likely fail outside the warranty period) and gunking up and the intake tract.

 

[DoubleWasp]

Originally Posted By: Trav
I figure if they were worth a P hole in the snow the manufacturer would put them on as OE.


Many many many manufacturers do. They just don't look like the aftermarket designs.

 

[DoubleWasp]

Originally Posted By: Trav
You assume all cars are built to a price point, some are not and still don't have one. They will sell you a $99 cheap POS catch can for your 1.5 million dollar Veyron to improve its performance.
Using an oil that doesn't go up in smoke like your mothers frying pan oil will probably eliminate much of the problem they are trying to fix with these things.


You realize that dry sump engines don't have the typical PCV system dragging air from the valve cover, right?

Some manufacturers don't have a crankcase ventilation system prone to sucking oil, and don't need that kind of external separator. Other manufacturers have simply been screwing up the job for decades, and continue to make changes to try and improve the situation.

VWAG is definitely one of those culprits.

 

[DoubleWasp]

Originally Posted By: itguy08
Originally Posted By: bubbatime

Thats not how that works.

1,000,000 - cars sold
$4 - the cost of one widget per car
$4,000,000 - FOUR MILLION dollars for the auto company to add a $4 widget per car, if they sell a million cars. And since businesses are in the habit of trying to cut cost, while trying to earn a buck, any and all extra 'widgets" that are really not needed are ixnayed.


Or you spend the $4, raise the price of the vehicle $10 and nobody will notice the $10 on a $30-40k vehicle. Few would dismiss a car over $10.

If it did the things claimed (HP gains, MPG gains, etc) then it would be a steal for manufacturers as it would be a cheap boost to CAFE...

You may even reduce warranty costs if it actually did something. The fact that a manufacturer of a can (supposedly the best) who owned a speed shop could not provide pictures of clean valves or before/after dyno #'s was all the data I needed to see. They are useless for stock applications. He also tried to say MPG would go down due to the valve deposits. Unfortunately for him I have records of nearly ever fill up for well over 100k miles in 1 and 30k in the other and MPG is roughly the same over all those miles.


You're throwing the baby out with the bath water.

His actions with his product do not determine what all catch cans everywhere do.

 

[DoubleWasp]

Originally Posted By: PeterPolyol
There are oil separators and labyrinths of various types on virtually all new engines. In the 70s-80s they were crude and oft built into the valve cover. Some more recent (post 2000's iterations) are cast right into the side of the block, because an oil/vapour separation function is so intended by the engineers, that they in-built it into the engine block casting. Manufacturers are to this day still patenting better and better mist/vapour separators, regardless of the "style" of PCV valve.

Yeah, it's worth something.


Indeed.

My Rams have a separator mounted on top of the valve cover. They have a type of woven fleece type material on the inside of them to remove oil vapor from the air before it goes into the turbocharger. Cummins (who is no idiot) believes that this system is under enough assault that they recommend changing it every 60k miles, and have a sensor that triggers a warning if the crankcase pressure builds to unacceptable levels (indicating the system is clogged).

Does refusing to maintain this system have penalties? It sure does. When I bought my second trucks and removed the intake pipe, I found something that looked like tar had made its way out of the pipe and into the turbocharger intake. Sensors in the intake tract looked like they were covered in solid obsidian rock.

This type of formation has resulted in the total destruction of engines.

Oil going into the intake tract can definitely cause knocking in gasoline engines, where they are concerned.

I can think of several engines from several different manufacturers just off of the top of my head that have chambers to catch oil before it reaches the intake tract and return it to the crankcase.

 

[SteveSRT8]

Originally Posted By: itguy08


If it did the things claimed (HP gains, MPG gains, etc) then it would be a steal for manufacturers as it would be a cheap boost to CAFE...

You may even reduce warranty costs if it actually did something. The fact that a manufacturer of a can (supposedly the best) who owned a speed shop could not provide pictures of clean valves or before/after dyno #'s was all the data I needed to see. They are useless for stock applications. He also tried to say MPG would go down due to the valve deposits. Unfortunately for him I have records of nearly ever fill up for well over 100k miles in 1 and 30k in the other and MPG is roughly the same over all those miles.


Correct, and an interesting point of agreement! Lots of variables here, hard to nail it down.

The sheer numbers of cars running today proves that catch cans are a "want", not a "need" for most applications. Every single car with a sump has oil in the intake.

And just like Trav said, Those who have huge amounts of oil in their blow by gasses may simply be revealing their oil's excessive volatility.

 

[Trav]

Sure some use pre heaters and all AFAIK use breather/vent tanks but so what? They still sell a catch can for a car that doesn't have or need one.
That still doesn't mean a catch can is an effective mechanical coalescer for very long due to its limited size and media type and amount, some have nothing inside and are basically totally useless. Even if it catches 1oz how many ounces didn't it catch? The one ounce makes little difference.

I would like to see a real test, something like a 1 qt of oil into smoke and draw the vapors through a catch can and see how much it catches. I would be surprised if it caught a couple of ounces.
That's like saying these band-aids are great they really help stop the bleeding when the guy has a artery spraying all over the place along with the cut on his finger.

 

[itguy08]

Originally Posted By: DoubleWasp
You're throwing the baby out with the bath water.

His actions with his product do not determine what all catch cans everywhere do.



So exactly what benefit do they serve? Sure they catch stuff. And that stuff has circulated through billions (maybe trillions) of engines without issue for the past 60 or so years when sealed PCV systems were required.

As the VW/Audi/BMW guys show they don't fix deposits in DI engines. In stock form, they don't give a MPG gain, they don't give a HP gain.

They do however lighten your wallet and collect "stuff".

 

[Trav]

For cars with no cat just dump it into the exhaust with venturi check valves or go real old school and just run a road draft tube down the back of the engine with some SS wool packed in it. Not the most environmentally friendly way but both really work. I use to have a few tubes kicking around from old SBC engines.

 

[SteveSRT8]

Hahaha, I can tell Trav remembers the stain that used to be on the roads in the old daze! Used to have to watch out when it first got wet...

 

[Trav]

For sure I remember! A little antifreeze/coolant at stop signs and red lights from cars with no overflow tanks was always good for a few laughs on 2 wheels too.

 

[spasm3]

Originally Posted By: Trav
For cars with no cat just dump it into the exhaust with venturi check valves or go real old school and just run a road draft tube down the back of the engine with some SS wool packed in it. Not the most environmentally friendly way but both really work. I use to have a few tubes kicking around from old SBC engines.




The down draft tube might be just the answer for DI. I think it would be easy to install. When the car is out of warranty, you could plumb it in to the exhaust right behind the converter.

 

[SHOZ]

Originally Posted By: Trav
Sure some use pre heaters and all AFAIK use breather/vent tanks but so what? They still sell a catch can for a car that doesn't have or need one.
That still doesn't mean a catch can is an effective mechanical coalescer for very long due to its limited size and media type and amount, some have nothing inside and are basically totally useless. Even if it catches 1oz how many ounces didn't it catch? The one ounce makes little difference.

I would like to see a real test, something like a 1 qt of oil into smoke and draw the vapors through a catch can and see how much it catches. I would be surprised if it caught a couple of ounces.
That's like saying these band-aids are great they really help stop the bleeding when the guy has a artery spraying all over the place along with the cut on his finger.
The ones I use are cheap ebay cans with nothing inside. They catch quite a bit. The key is to put them in a cooler than engine compartment area and it will condense the vapors. Far from useless.