Talk to me about oil catch cans and intake valve deposits

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PWMDMD

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The 2025 Subaru Forester is my first DI only vehicle I plan to keep for a while and I'm trying to minimize intake valve deposits as much as possible. So far it looks like low NOACK oil would be a good choice and I keep reading about catch cans. I understand the concept perfectly well, I just don't know if they actually do anything to help for the 2.5 N/A engine in my Subaru.

Does anyone think Valvoline R&P has any advantage here? Whatever the magic sauce is will also work its way through the system and help keep the intake valves cleaner?
 
In my opinion, from what I've lightly gathered. Don't waste your time or effort. I've never done it so take that for what it's worth. Did you see the recent Honda oil filter c&p with r&p being used? That filter was plugged. ha!
While other vehicles seems nothing to note in the filter. Seems the Honda in the above mentioned thread might of been really dirty but I do think the r&p did something in that case.
 
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Not going to touch the catch can debate. I have my own opinions and experiences. Some have others and I will leave it at that.

Whether or not R&P has any effect on IVD depends a lot on ventilation design and can vary quite a bit based on that. Valve stem seals could also play a part. Personally, I wouldn't count on it doing much to mitigate deposits on the valves.
 
OIls with a low SA are preferred for ivd and I remember the old m1 formula esp being touted as great for ivd since it was 0.6% but the new ones are higher at 0.8 but still low in general. Catch cans aren't expensive the one I put on my truck was around 40 bucks from amazon and catches some junk but not as much as I'd thought at first. I think some like to run vw 504/507 to help ivd.

There's a good bit of general ivd discussion on here and other threads.
edyvw

Post in thread 'Restore & Protect - GDI Intake Valve Deposits'

buster said:
That's been the general theory but from what I've seen they all get deposit buildup. There really isn't much you can do and it doesn't appear to be a problem in most cases. Most synthetics today have a Noack <10%, especially EP lines. Noack actually isn't the only concern either. Ash level, oxidation resistance of base oil and solvency. The oil coming in contact is still whole oil in mist or vapor form.

It would be interesting to run a test of MB229.52 vs FS HPL, Red Line and Amsoil SS in terms of IVD's.

HPL mentions how "These oils are formulated with specifically chosen esters...
Click to expand...
 
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PWMDMD said:
The 2025 Subaru Forester is my first DI only vehicle I plan to keep for a while and I'm trying to minimize intake valve deposits as much as possible. So far it looks like low NOACK oil would be a good choice and I keep reading about catch cans. I understand the concept perfectly well, I just don't know if they actually do anything to help for the 2.5 N/A engine in my Subaru.

Does anyone think Valvoline R&P has any advantage here? Whatever the magic sauce is will also work its way through the system and help keep the intake valves cleaner?
Click to expand...

If the cause of intake deposits is the oil, then an oil that prevents deposits (ester/AN or what VRP uses) will have a positive effect. But the majority of intake valve deposits is caused by unburned fuel and flow reversal imo.

if you use an oil that is prone to causing deposits, that will not help the situation any.
 
What about engine designs, like Toyota's D4S, that have port and direct injection?
Would the potential benefit of the catch can be reduced?
 
rijndael said:
What about engine designs, like Toyota's D4S, that have port and direct injection?
Would the potential benefit of the catch can be reduced?
Click to expand...
Reduced enough to where I wouldn't bother to put it on unless it's known to have a lot of pcv consumption but those engines aren't.
 
rijndael said:
What about engine designs, like Toyota's D4S, that have port and direct injection?
Would the potential benefit of the catch can be reduced?
Click to expand...
I don't think there's any indication for a catch can there.
 
Are the potential deposits from PCV systems impacting intake runner systems too?
Broader speaking, is the problem more than just intake valve deposits?
 
In my mind, a CC is going to capture oil that will not have to fly through your intake valve ports. The question is, how much better will that prevent IVDs for your specific situation, vs leaving it stock? Too many variables to measure.

I had a J&L catch can kit installed on my 2022 Nissan Frontier for about 40K miles. It required regular maintenance in cold weather, like a draining every 2 weeks or risk filling the can to the top. It would fill with condensed moisture and some oil. In the warmer months I would get ~2-3 ounces of what looked/smelled like gassy used engine oil w/ no moisture per 5K oil change.

I removed the CC when I gave the truck to my daughter who lives 750miles away because of the maintenance required when having one in place.
 
Subaru DI engines have a pretty effective AOS built into the engine. Adding another one should still help, but I wouldn't bother. They can cause issues like becoming clogged with ice and then blowing engine seals, and you aren't likely to get warranty if they cause problems.

The fuel injectors on the FA engines (and I'm guessing the FB as well) are designed to spray some fuel onto the intake valves while they're open. As a result, the tops of the valves don't get all that dirty, and they can be kept cleaner by using quality fuel or occasionally using some PEA fuel system cleaner. The intake tract and valve stems will still get dirty, but it's unlikely that this will ever cause any running issues.

Noack has little to no effect on valve deposits. Studies show that the composition of the IVD on GDI engines closely matches that of the engine oil, which means that it's liquid oil droplets that are depositing on the valves, not vaporized oil.

As to whether VRP would help, it's anybody's guess. Calcium and magnesium detergents don't help. They just end up becoming part of the deposits. Valvoline's magic sauce may work just the same.
 
I can't add to what others have already said other than there is no definitive way to mitigate them. I'm not convinced Noack, low SAPS makes a difference. I'm intrigued by how VRP would do though. Also curious if VW's method of periodically running the engine at 4k rpms for 20 mins helps.
 
There is no "catch can" controversy. There are millions upon million of vehicles without them-with million and millions of accumulative miles......
 
My take is… can’t hurt, might help, not expensive. Probably a waste of $ for NA daily driver. For forced induction vehicles driven hard, not a bad idea.
 
twX said:
Subaru DI engines have a pretty effective AOS built into the engine. Adding another one should still help, but I wouldn't bother. They can cause issues like becoming clogged with ice and then blowing engine seals, and you aren't likely to get warranty if they cause problems.

The fuel injectors on the FA engines (and I'm guessing the FB as well) are designed to spray some fuel onto the intake valves while they're open. As a result, the tops of the valves don't get all that dirty, and they can be kept cleaner by using quality fuel or occasionally using some PEA fuel system cleaner. The intake tract and valve stems will still get dirty, but it's unlikely that this will ever cause any running issues.

Noack has little to no effect on valve deposits. Studies show that the composition of the IVD on GDI engines closely matches that of the engine oil, which means that it's liquid oil droplets that are depositing on the valves, not vaporized oil.

As to whether VRP would help, it's anybody's guess. Calcium and magnesium detergents don't help. They just end up becoming part of the deposits. Valvoline's magic sauce may work just the same.
Click to expand...
Does this mean the oil is from the valve stem seals?
 
I did buy some Subaru PEA carbon cleaner and the accompanying carbon cleaner tool. I also have the latest TSB instructions which are pretty simple and so I was thinking of running a treatment every 10K miles. Does running PEA too often kill the cat?
 
Almost every manufacturer can resolve (or greatly reduce) the IVD issue by employing the dual fuel port/direct injection system. They won't though because of cost and some complexity. They know that 99% of the consumers either know nothing about IVD, or don't care enough to do the requisite maintenance cleaning of the intake valves/ports. They count on them just purchasing another car when problems arise. And it seems they've hedged their bets correctly.
 
shortyb said:
Almost every manufacturer can resolve (or greatly reduce) the IVD issue by employing the dual fuel port/direct injection system. They won't though because of cost and some complexity. They know that 99% of the consumers either know nothing about IVD, or don't care enough to do the requisite maintenance cleaning of the intake valves/ports. They count on them just purchasing another car when problems arise. And it seems they've hedged their bets correctly.
Click to expand...
I'm disappointed Subaru hasn't adopted Toyota's D4S since it was already adapted to the 2.4 in the BRZ.
 
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