To Catch Can or Not to Catch Can

[BaneKotaKeena]

Just checked my J&L Oil Separator at 5-600 miles since install and this is what came out. Not a lot for sure (maybe an 1/8th of the small can) but it is doing what it says. I plan to re-check every couple months, noting mileage at empties.

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[CampThree]

I wonder why the auto manufactures don't install them at the factory.

That was my very first thought as well.

 

[BaneKotaKeena]

That was my very first thought as well.

Likely because most people dont want more things to have to remember to do as far as maintenance is concerned.

There is also the degradation that is inherent in engines and that many people just take their vehicles to the dealer they bought it from whenever anything goes wrong.

Taking steps to ensure less trips to the dealer and longer lasting products are not as high on the manufacturer priority list as they should be.

 

[ShadowsPapa]

However I've seen the oil amount some have been catching and Holy Moly Batman! Where's that all coming from!?

Be VERY careful of the "you need one" group that will show a full can - that looks like an over-priced starbucks drink. These also catch condensation and mix it well with the oil - an emulsion - and some of those I mention claim "look at all the oil! That's 8 ounces of oil!" when in fact, it's about 1 or 2 ounces, the rest is water.
YES, water and oil can, will/do mix and it looks like starbucks crap.
If it's really oil, it will look identical to the oil in your pan - EXACTLY like it in all ways, because face it, it would be oil from the pan/crankcase.
So unless it's exactly like the oil on the dipstick or out of the pan, it's not oil, it's an emulsion - water and oil.
And if you have a catch can truly pull 8 ounces of real oil - that means your oil is down by 8 ounces plus a bit more.
So unless it's looking exactly like the oil in the crankcase - and not tan or brown, and if it's still a lot, you need to check your oil level and add some.
Catch cans don't make oil - it's coming from your crankcase - so whatever is in that can is no longer in the engine, your oil level will be down by at least what's in the can.

I wonder why the auto manufactures don't install them at the factory.

Because if all systems are working ok, it's just not needed.
That's a fact -but you know how Jeep people are - they have it so it's necessary and always is the only fix and if they suggest it's not necessary, then they are contradicting themselves and admitting they don't really need it.

These motors don’t need a catch can. There’s a whole long thread on it. If you’re actually getting significant oil blow-by then you have other problems.

If pressing the pedal harder doesn’t break your tires loose then a pedal commander isn’t going to either.

Exactly - if you have excessive oil consumption via the PCV, you have other issues that need to be addressed. Too often a catch can is a bandaid and the real problem is ignored because the catch can has become a cool Jeep thing. All the really cool guys are running them, they must be necessary!
And their proof that they are necessary is too often a can full of Starbucks crap - not pure oil.

There are indeed huge threads on it from way back.

If there's excessive oil - you may have issues like a faulty PCV, or excessive blow-by, or are driving in a way to really ramp up the vacuum - like a manual transmission downshifted at a high road speed causing the engine to jump to extremes in vacuum - pulling excessive air from the crankcase. Driving habits, especially with a stick, can cause excessive oil consumption through modern PCV systems.
In the past, the PCV was a VALVE with a shuttle that would literally close under high vacuum conditions such as a downshift that caused vacuum to jump to the max. It would pull the shuttle in the PCV VALVE closed to avoid excessive crankcase vacuum and pulling oil.
These don't have that shuttle - not that I know of, maybe Hootbro or Charles can comment, but I believe these are more like my sandblast and beadblast cabinets with cyclone separators between the cabinet and vacuum that spin out anything except air.

My oil level doesn't go down to where I can notice it between oil changes. What's that tell me? It's not sucking oil out of the crankcase and my rings must be sealing fine. You always lose SOME past the rings, it's impossible to not lose a tiny bit so some drop is "normal".

 

[PuddleJumper]

Be VERY careful of the "you need one" group that will show a full can - that looks like an over-priced starbucks drink. These also catch condensation and mix it well with the oil - an emulsion - and some of those I mention claim "look at all the oil! That's 8 ounces of oil!" when in fact, it's about 1 or 2 ounces, the rest is water.
YES, water and oil can, will/do mix and it looks like starbucks crap.
If it's really oil, it will look identical to the oil in your pan - EXACTLY like it in all ways, because face it, it would be oil from the pan/crankcase.
So unless it's exactly like the oil on the dipstick or out of the pan, it's not oil, it's an emulsion - water and oil.
And if you have a catch can truly pull 8 ounces of real oil - that means your oil is down by 8 ounces plus a bit more.
So unless it's looking exactly like the oil in the crankcase - and not tan or brown, and if it's still a lot, you need to check your oil level and add some.
Catch cans don't make oil - it's coming from your crankcase - so whatever is in that can is no longer in the engine, your oil level will be down by at least what's in the can.



Because if all systems are working ok, it's just not needed.
That's a fact -but you know how Jeep people are - they have it so it's necessary and always is the only fix and if they suggest it's not necessary, then they are contradicting themselves and admitting they don't really need it.



Exactly - if you have excessive oil consumption via the PCV, you have other issues that need to be addressed. Too often a catch can is a bandaid and the real problem is ignored because the catch can has become a cool Jeep thing. All the really cool guys are running them, they must be necessary!
And their proof that they are necessary is too often a can full of Starbucks crap - not pure oil.

There are indeed huge threads on it from way back.

If there's excessive oil - you may have issues like a faulty PCV, or excessive blow-by, or are driving in a way to really ramp up the vacuum - like a manual transmission downshifted at a high road speed causing the engine to jump to extremes in vacuum - pulling excessive air from the crankcase. Driving habits, especially with a stick, can cause excessive oil consumption through modern PCV systems.
In the past, the PCV was a VALVE with a shuttle that would literally close under high vacuum conditions such as a downshift that caused vacuum to jump to the max. It would pull the shuttle in the PCV VALVE closed to avoid excessive crankcase vacuum and pulling oil.
These don't have that shuttle - not that I know of, maybe Hootbro or Charles can comment, but I believe these are more like my sandblast and beadblast cabinets with cyclone separators between the cabinet and vacuum that spin out anything except air.

My oil level doesn't go down to where I can notice it between oil changes. What's that tell me? It's not sucking oil out of the crankcase and my rings must be sealing fine. You always lose SOME past the rings, it's impossible to not lose a tiny bit so some drop is "normal".

Thanks for the insight. I'll just check for blow by like someone else mentioned. But i'm not seeing a good reason for a catch can rn. Seems to fall under that whole steering stabilizer fixes death wobble thing. Odds are its just masking a bigger issue. I'm hoping summer fuel will net a noticeable difference. And the peddle monster. I don't like how the throttle feels like a suggestion pedal and not a gas pedal.

 

[Charles 236]

There is still a valve in the PCV valve, but in normal operation it would rarely need to close to stop oil from coming into the intake manifold. This is because the right exhaust camshaft has a centrifugal oil separator on it near the PCV valve. It spins out liquid oil, so only crankcase vapor is admitted into the PCV valve. In an extreme case, like climbing at a steep angle (with engine revs relatively high) oil MIGHT get past the separator and make it into the PCV. These engines have very good oil drainage, that is, they don't tend to fill the heads up with more oil than can drain back to the oil pan. If you frequently climb at angles and engine speeds that cause liquid oil to make it past the separator (through the PCV valve), then a catch can would be beneficial. But it is not necessary in normal operation, and it adds another point to be maintained.

Use a catch can if you want to, as long as you take care to empty it as needed it will not do any harm. In other words, Whatever slays your dragon.

 

[JulesAo]

I just installed one last month and it caught all this in three weeks.

 

[PuddleJumper]

Op, if I’m understanding correctly, your performance measure is in being able to “chirp” the tires so under the same conditions now, you can’t so you have a peddle monster coming and considering an oil catch can.

I think there’s a few factors to consider if you’re experiencing the “factory performance” has diminished some. I’m speculating here but if I was concerned just like you, I would be looking at these points.

1. gas that’s either summer or winter blend might effect this??
2. Do you have blow by? Turn on your engine and take off your oil fill cap. Do you feel a rush of air blowing out? If yes, you should install a catch can. If no, then there’s no oil particles being tossed into your air intake tube from the PCV and a can isn’t needed.
3. If your answer to blow by is YES , you need to pull your mass air flow sensor (it’s on the intake tube just before the bend, facing the front with two wires) and spray it off with MAF sensor cleaner. Don’t use brake clean and don’t wipe it or touch the sensor prong with a rag. Spray clean it and put it back in.
If your answer is NO, do the cleaning anyway at every oil change.
4. How’s your air filter?
5. You mentioned the thing about the computer “learning” how you drive. If your not chirping the tires every time you take off, it’s learning you don’t need that performance.

That’s my practice and I can “chirp” my tires all day long but I don’t because I’m old and mature and don’t need to impress the girls. I got mine already and if I was to do a chirp or brake stand, I’d get a smack upside the head or I’d probably break something.

almost forgot. Checked blow by, nothing, not a molecule of air moving out of the oil fill cap. Still waiting on the pedal monster. I'm still hopeful it let me drive my Mojave the way it was off the lot. Yeah i get most people never want to snap the tires loose. To me its just weird that I can floor it or 3/4 it and it takes off all the same. I just want it to feel like a gas pedal again, not a suggestion pedal. thx for the blow by instructions, i'll skip on the catch can.

 

[starrskream]

I just installed one last month and it caught all this in three weeks.

like shadow said above, that’s not purely oil.
It’s an emulsion of oil and water.
If that’s purely oil you have a bigger problem that needs repairs.

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