J&L OIL SEPARATOR CO

GAMark · May 13

Catch can added last night. Will add pics later.

Edited May 30 by GAMark

riddler · May 28

On 5/13/2026 at 6:26 AM, GAMark said:

Catch can add last night . Will add pics later.

I have about 15k miles on my install definitely catches fuel/ oil burpup

TrueBlue · May 28

Question on this. If the Separator is between the intake manifold and the left valve cover, but the PCV valve hooks directly from the right valve cover to the air intake tube, isn't that latter process still adding oil vapor from the oil pan/crankcase into the intake valves?

Pryme · May 28

1 hour ago, TrueBlue said:

Question on this. If the Separator is between the intake manifold and the left valve cover, but the PCV valve hooks directly from the right valve cover to the air intake tube, isn't that latter process still adding oil vapor from the oil pan/crankcase into the intake valves?

There are multiple very long threads on this contraption. A quick search will give you plenty of reading to decide if it’s right for you.

TrueBlue · May 29

I've read a few. I just don't think my question has been answered. I find it hard to understand how the catch can can be capturing all of the vapor when it isn't in line with the PCV.

Pryme · May 29

10 hours ago, TrueBlue said:

I've read a few. I just don't think my question has been answered. I find it hard to understand how the catch can can be capturing all of the vapor when it isn't in line with the PCV.

It’s my personal opinion that the only one benefiting from this is the manufacture. It’s completely unnecessary.

Edited May 29 by Pryme

TrueBlue · May 29

Given the fact that there appears to be two separate routes for the vapors to travel back to the intake valves I would tend to agree. If there was only one, and the can was in line, between the pan and the intake I would be much more inclined to equip my truck with one of these.

There is no doubt that direct injection does result in carbon build-up on the valves. What is needed is a way to avoid this entirely. As well as that which comes from unburned oil vapors. But until the next technological break-through I guess we're stuck with the issue, or both.

The thought of tearing the top end of my engine apart in order to blast the valves with walnuts or some such is not a welcome one.

riddler · May 29

17 hours ago, TrueBlue said:

I've read a few. I just don't think my question has been answered. I find it hard to understand how the catch can can be capturing all of the vapor when it isn't in line with the PCV.

It may not be capturing all of it, it does capture a good amount. Im glad I installed mine early, hopefully it will slow down valve carbon build up.

riddler · May 29

4 hours ago, TrueBlue said:

Given the fact that there appears to be two separate routes for the vapors to travel back to the intake valves I would tend to agree. If there was only one, and the can was in line, between the pan and the intake I would be much more inclined to equip my truck with one of these.

There is no doubt that direct injection does result in carbon build-up on the valves. What is needed is a way to avoid this entirely. As well as that which comes from unburned oil vapors. But until the next technological break-through I guess we're stuck with the issue, or both.

The thought of tearing the top end of my engine apart in order to blast the valves with walnuts or some such is not a welcome one.

You make a good point. I will look at the probability of installing 2. Possibly capturing all of the vapors.

TrueBlue · May 29

You might want to talk to a mechanic about that. if the PCV inlet to the airbox happens to be upstream of the MAP sensor it might cause an issue. Or possibly if putting the catch can in line between the valve cover and the intake might result in what would amount to a vacuum leak?

Edited May 29 by TrueBlue

riddler · May 29

Yes I was speaking more tongue and cheek. Only time and miles will tell if the catch can works. I have 31k miles. I figure it is worth the money spent if it slows the carbon process.

If not well I can forward my knowledge on to others.

Pryme · May 29

12 minutes ago, riddler said:

Yes I was speaking more tongue and cheek. Only time and miles will tell if the catch can works. I have 31k miles. I figure it is worth the money spent if it slows the carbon process.

If not well I can forward my knowledge on to others.

Do you have a second truck that you will drive next to the catch can truck to compare the two? More of a joke but there is no way to compare how yours is stacking up to a truck without the can.

these trucks are used and abused by companies for a couple hundred thousand miles all day long. None of them have a catch can.

riddler · May 29

3 minutes ago, Pryme said:

Do you have a second truck that you will drive next to the catch can truck to compare the two? More of a joke but there is no way to compare how yours is stacking up to a truck without the can.

these trucks are used and abused by companies for a couple hundred thousand miles all day long. None of them have a catch can.

There are plenty of owners here not using the CC to compare too. You obviously arent what truck do you drive? Miles?

riddler · May 29

Just now, riddler said:

There are plenty of owners here not using the CC to compare too. You obviously arent what truck do you drive? Miles?

Man if I get 200k out of this motor, i cant ask for anything more!

TrueBlue · May 29

Well, if the can catches any vapor at all, that it turns into liquid, it should amount to a lesser buildup on the valves. Or so I would think. I just don't know to what extent it might amount to.

I installed a catch can on my 2018 Fat Boy, and I did have to empty it from time to time. That small amount would have been sent straight into the throttle body, so I know it was doing at least some good. I would think the same would apply here.

Some of us like to hedge our bets. Especially given that we don't get to write our "investment" off like some companies do.