Pour it out? Really?

[Dr. Righteous]

This was posted in the PCV oil catch can thread and I don't think anyone saw it. Hopefully it can spur some discussion.


Alrighty; Have a different point of view.
Follow me on this.
The PCV system picking up oil mist is nothing new. Its Positive Crankcase ventilation. The engine oil being whipped up into a fury by heat and the spinning cranked reciprocating rods is how it works. The air in there is a misty, oily, atmosphere. Blowby contamination is a given. It is why you have to change the oil.
I would say MOST of the oil affected by the blow by stays there. SOME is picked up by the PCV and goes into the intake with negative results in engine operation.
I see NO PROBLEM with this captured oil draining right back into the crank case.
Keep in mind if you run an expensive synthetic oil you are throwing dollars in the trash when you pour that out. Yes, it is contaminated, but so is all the oil in the crank case.
That is why it is filtered, that is why you change it.
So what I would see as a very effective catch can solution is one that separated the air/oil and then drained the oil back to the crank case.
Keep in mind; high quality engine oil is DESIGNED to deal with contaminates like blow by containing fuel, moisture, etc, etc. it is much more tolerant to the negative effects of the blow-by contaminates have on straight mineral oils and it has very high detergent properties to break up gummy deposits.
When out stick your noise in the catch can; it does smell like gas some because it pulls some of that out of the crank case. The truth is, your crank case is already full of that stuff. Pouring that oil out is wasting oil.

Now, I'm not saying this whole catch can thing is a gimmick; it is effective. But for the average street vehicle that serves a more utilitarian role I think it is poorly executed because it is a wasteful design.

 

[Burla]

Some people would darn near kill their mother to save a couple bucks. I say dump it and if you feel like putting something back, put a little clean oil back. What is a catch cans capacity worth of oil, a buck?

 

[catch 22]

Dump it, putting it back into the engine kinda reminds me of........ever see a dog puke and then eat it again, yeah it reminds me of that.

 

[ExpressRules]

What's a Catch Can ?????

 

[DannyMK2]

This was posted in the PCV oil catch can thread and I don't think anyone saw it. Hopefully it can spur some discussion.


Alrighty; Have a different point of view.
Follow me on this.
The PCV system picking up oil mist is nothing new. Its Positive Crankcase ventilation. The engine oil being whipped up into a fury by heat and the spinning cranked reciprocating rods is how it works. The air in there is a misty, oily, atmosphere. Blowby contamination is a given. It is why you have to change the oil.
I would say MOST of the oil affected by the blow by stays there. SOME is picked up by the PCV and goes into the intake with negative results in engine operation.
I see NO PROBLEM with this captured oil draining right back into the crank case.
Keep in mind if you run an expensive synthetic oil you are throwing dollars in the trash when you pour that out. Yes, it is contaminated, but so is all the oil in the crank case.
That is why it is filtered, that is why you change it.
So what I would see as a very effective catch can solution is one that separated the air/oil and then drained the oil back to the crank case.
Keep in mind; high quality engine oil is DESIGNED to deal with contaminates like blow by containing fuel, moisture, etc, etc. it is much more tolerant to the negative effects of the blow-by contaminates have on straight mineral oils and it has very high detergent properties to break up gummy deposits.
When out stick your noise in the catch can; it does smell like gas some because it pulls some of that out of the crank case. The truth is, your crank case is already full of that stuff. Pouring that oil out is wasting oil.

Now, I'm not saying this whole catch can thing is a gimmick; it is effective. But for the average street vehicle that serves a more utilitarian role I think it is poorly executed because it is a wasteful design.

what about the older cars that vented to the atmosphere? should we slap catch cans on them so we can collect and dump that back into the crank case?

 

[audio1der]

I wondered about this, and even if it were part of the intended design of the engine. In the end, I figured I would rather add fresh oil if required. I, along with some others run long interval change oil. Adding a touch of fresh oil if required would only be a good thing for engine longevity IMO.

 

[Dr. Righteous]

I wondered about this, and even if it were part of the intended design of the engine. In the end, I figured I would rather add fresh oil if required. I, along with some others run long interval change oil. Adding a touch of fresh oil if required would only be a good thing for engine longevity IMO.

It seems that there is this idea that oil in the catch can is "bad oil" some how. The same contaminates that are in the catch can oil is in your crank case already. That is where the oil came from. The difference is that oil was whipped into a mist and when out the PCV. The point I'm trying to make here is the unfortunate BAD design of the PCV causes the engine to consume oil and also suffer the detrimental effects of oil in the intake patch and fuel mixture. A catch can to separate the oil out is part of the solution, but if you pour it out you have not solved the oil consumption problem. You have to add new oil to replace it.

And yeah, I'm looking at dollars and cents.
Mobil 1 isn't cheap and the Hemi takes 7 quarts. That is an expensive oil change no matter how you look a it. Between change intervals; how much of that oil are you pouring in the trash?

 

[14hemiexpress]

It seems that there is this idea that oil in the catch can is "bad oil" some how. The same contaminates that are in the catch can oil is in your crank case already. That is where the oil came from. The difference is that oil was whipped into a mist and when out the PCV. The point I'm trying to make here is the unfortunate BAD design of the PCV causes the engine to consume oil and also suffer the detrimental effects of oil in the intake patch and fuel mixture. A catch can to separate the oil out is part of the solution, but if you pour it out you have not solved the oil consumption problem. You have to add new oil to replace it.

And yeah, I'm looking at dollars and cents.
Mobil 1 isn't cheap and the Hemi takes 7 quarts. That is an expensive oil change no matter how you look a it. Between change intervals; how much of that oil are you pouring in the trash?

Look into the cost per miles it's nothing it's probably even cheeper then my wife's altima that's 5qts of conventional but every 3750 Not 10k

I'm just not a fan of pouring oil back in... I won't put break fluid back in the master cylinder after bleeding my break... Just helps me sleep at night.

 

[DannyMK2]

It seems that there is this idea that oil in the catch can is "bad oil" some how. The same contaminates that are in the catch can oil is in your crank case already. That is where the oil came from. The difference is that oil was whipped into a mist and when out the PCV. The point I'm trying to make here is the unfortunate BAD design of the PCV causes the engine to consume oil and also suffer the detrimental effects of oil in the intake patch and fuel mixture. A catch can to separate the oil out is part of the solution, but if you pour it out you have not solved the oil consumption problem. You have to add new oil to replace it.

And yeah, I'm looking at dollars and cents.
Mobil 1 isn't cheap and the Hemi takes 7 quarts. That is an expensive oil change no matter how you look a it. Between change intervals; how much of that oil are you pouring in the trash?

the catch can collects a good amount of moisture along with the oil mist. thats the stuff i wouldnt want to be dumping back into the motor. if you were to separate the oil and water, then maybe. the amount of oil my catch can would pick up in a 5k mile interval was not measurable on the dipstick to even warrant topping off. maybe yours is different?

how often do you change your oil? theres a good possibility that your wasting more money changing you oil too soon then you are by dumping out your catch can and topping off with fresh oil. something to consider if your counting pennies.

 

[twodips]

It ain't much in the scope of things...

 

[Dr. Righteous]

the catch can collects a good amount of moisture along with the oil mist. thats the stuff i wouldnt want to be dumping back into the motor. if you were to separate the oil and water, then maybe. the amount of oil my catch can would pick up in a 5k mile interval was not measurable on the dipstick to even warrant topping off. maybe yours is different?

how often do you change your oil? there a good possibility that your wasting more money changing you oil too soon then you are by dumping out your catch can and topping off with fresh oil. something to consider if your counting pennies.

Moisture in the crankcase is normal to a certain extent. These engines have to run in very humid tropical zones and on rainy days. The heat in the crank case evaporate it and it goes out the PCV.

My oil change intervals are 6000 miles or 6 months. With Mobil 1. Typically nearly a quart would be consumed in that interval on the old 2004 hemi Durango. I'm sure that quart went via the PCV.

 

[DannyMK2]

Moisture in the crankcase is normal to a certain extent. These engines have to run in very humid tropical zones and on rainy days. The heat in the crank case evaporate it and it goes out the PCV.

yes its normal, but now that you've extracted and collected it why would you want to dump it back in?

My oil change intervals are 6000 miles or 6 months. With Mobil 1. Typically nearly a quart would be consumed in that interval on the old 2004 hemi Durango. I'm sure that quart went via the PCV.

if you were to do an oil analysis im sure you would find that your changing your oil way before you need to with a 6k mile interval on synthetic. if you ran your oil longer you would save more money then dumping what you collect from your catch can back into the motor.

its your truck, do what ever you want. it just doesnt make much sense to me.

 

[14hemiexpress]

If you were to do an oil analysis im sure you would find that your changing your oil way before you need to with a 6k mile interval on synthetic. if you ran your oil longer you would save more money then dumping what you collect from your catch can back into the motor.

its your truck, do what ever you want. it just doesnt make much sense to me.

This and I see the OP's truck is a 14. I know all the 14s have a oil life meter and the owners manual states by oil life meter or 10k whitch ever is first. Mine was always on par with the olm at 5k it showed right at 49-51% left.

 

[kris72079]

I guess my first question would be why would someone install a catch can on a relatively new daily driver truck? I come from the hot rod world and we use them in boosted applications or bigger shot nitrous applications. If you're collecting more than a VERY small amount of oil in a catch can in between regularly scheduled oil changes you've got something going on. I can understand maybe consuming like a quart over 10k miles as some have suggested, but more than that??? Just as a for instance, my SBC in my toy is a 12.5:1 motor with a 250 shot of nitrous and I handle crankcase pressure with just atmospheric venting with no excessive oiling issues. I obviously have deleted EGR and PCV systems for interior cleanliness of the motor over a bit of "being green". But to have the necessity to adopt a catchcan setup on a supposed healthy stock street driven motor? Not necessary unless you've got a bigger issue. That's just my angle on even installing a catch can setup in the first place. As far as keeping or dumping your collection? Well, how much do you need to retain that few ounces?

 

[THETANK]

When I had a catch can on my 14 it would collect when driving in the city but when on the highway (4000+ miles) it was bone dry, what's the reason??????

 

[Wild one]

I'm pretty sure the Hellcat recycles the oil back into the crankcase from it's factory valve cover oil separator,i'd guess it's done that way as the average person would never think of dumping a factory installed catch can.

 

[twodips]

This and I see the OP's truck is a 14. I know all the 14s have a oil life meter and the owners manual states by oil life meter or 10k whitch ever is first. Mine was always on par with the olm at 5k it showed right at 49-51% left.

I wait until at least 10k before changing otherwise I'm just dumping money.

 

[Dr. Righteous]

yes its normal, but now that you've extracted and collected it why would you want to dump it back in?

Forget the idea of "dumping it back in". Consider a different designed catch can where the gathered oil is drained back to the engine crankcase immediately and is assimilated back into the rest of the engine oil immediately. Any moisture is evaporated.

if you were to do an oil analysis im sure you would find that your changing your oil way before you need to with a 6k mile interval on synthetic. if you ran your oil longer you would save more money then dumping what you collect from your catch can back into the motor.

its your truck, do what ever you want. it just doesnt make much sense to me.

Understood; I could go further with an elaborate filtration system and squeeze even more mileage from the oil. But what was more important was an easy to follow maintenance routine. Oil change twice a year. January and July. Also when the miles pile up on the vehicle; one way you gauge the health of the engine is oil consumption. Is it burning a little oil or is the PCV eating it?

 

[Casper]

It seems that there is this idea that oil in the catch can is "bad oil" some how. The same contaminates that are in the catch can oil is in your crank case already. That is where the oil came from. The difference is that oil was whipped into a mist and when out the PCV. The point I'm trying to make here is the unfortunate BAD design of the PCV causes the engine to consume oil and also suffer the detrimental effects of oil in the intake patch and fuel mixture. A catch can to separate the oil out is part of the solution, but if you pour it out you have not solved the oil consumption problem. You have to add new oil to replace it.

And yeah, I'm looking at dollars and cents.
Mobil 1 isn't cheap and the Hemi takes 7 quarts. That is an expensive oil change no matter how you look a it. Between change intervals; how much of that oil are you pouring in the trash?

That whipping into mist draws out water vapor too which definitely degrades your oil if allowed to remain in the crankcase.

Catch cans wont save the planet, but if you got the dough its cheap piece of mind.

Dump it !

 

[Dubstep Shep]

Essentially this is what a true dry sump or vac pump system does. It recirculates the oil back into the system.