Would a PCV catch can be worthwhile?

[cwilliamsws6]

When my coworker and I did the spark plugs on my pathfinder a few weeks ago we noticed a small amount of oil on the intake plenum gasket and up in the intake plenum. I've also noticed on cold starts my exhaust smells a bit like oil.

Would adding a PCV catch can be worthwhile?

 

[NYEngineer]

I put one on my 09 Suburban after smoking out a parking lot once. It was weird. Never happened before. I installed the Moroso can and it's been fine ever since. I drain out a little bit every oil change.

 

[JTK]

It's tough to say if they do anything measurably positive. I have one on the VQ38DD engine in my 2022 Frontier. It collects a disturbing amount of moisture laden oil in the winter months. So much so, you have to be on top of draining it every 1-2K miles. In the warm months, it may have 2 ounces per 5K mile oil change interval. You're still going to have gasses and aerosols pass right through the catch can and across those pesky dry intake valves on a DI engine.

 

[carviewsonic]

I have a PVC catch can on my Impala. Collects 1-2 oz of oil during an OCI and collects an oil/moisture mix in cold weather. I would rather have the oil in the catch can than the intake and the intake valves. I think it's worthwhile on DI engines, and that it helps to reduce (though not eliminate) intake valve deposits.

 

[dnewton3]

As a generalization:
- For DI engines, they are certainly a worthwhile consideration. Plenty of YT videos out there; check out the one by Engineering Explained - it's detailed and very informational.
- For PFI engines, it's not really a necessity by any means. It can help but the improvements would be much smaller relative to DI systems.


I'll add this caveat ... each engine brand/type/series has pros and cons. My new 2023 MX-5 is a DI only engine and I thought it would greatly benefit from a catch-can. So I got a really nice one; made near me in Indy (very high quality unit and looks "stock" when installed). I've run it for 6k miles now, and have caught diddly squat. Why? Because apparently the little 2.0L in the MX-5 has a very good block-mounted PCV system, and so there's just not a lot of vapors making their way up to the intake. A catch-can can only "catch" what is present, after all.

My point is that if the DI system in a vehicle is paired with a very effective PCV system, you're maybe not going to see a lot caught in the can. But for systems which seem to puke a lot up to the intake, I think they are a good idea.

 

[Dave Hess]

It wouldn’t hurt to install and check every 3 months.

 

[Invisible]

Would adding a PCV catch can be worthwhile?

Yes, absolutely.

 

[twX]

Catch cans can sometimes have issues with moisture freezing and blocking the PCV system, which can cause major issues like blown seals. It's something to keep in mind if you do short trip driving in the winter.

Excessive oil in the intake can be a sign of a bad PCV valve. It doesn't sound like yours is excessive, but maybe check the PCV first before considering a catch can.

Oily exhaust on cold start can be caused by leaky valve guides. Stinky exhaust is normal before the cat warms up, but visible white/blue smoke isn't.

 

[SHOZ]

I have two on my Gen Coupe 2L turbo. Here's a pic of what I got out of both. The oil on top is from the fresh air makeup side and the water gunk is from the PCV line. This was 5k miles in the summer. Humidity makes for a lot of water in the blowby.

 

[Vercingetorix]

Better to burn it than collect it.

 

[SubieRubyRoo]

It wouldn’t hurt to install and check every 3 months.

I’d say at least every 3 tankfuls, especially when you first install, and more frequently in winter. On my F150, I get about an ounce of condensate every 6k miles or so. In winter, I nearly fill the cup every month. In summer, it’s essentially just add pack (I got a UOA on the collections) and in winter it’s a very watery snot that if you found it under the oil cap you’d think you had a blown headgasket.

 

[dfarr67]

I run good quality air/oil separators on all my vehicles.

 

[SHOZ]

Winter and self draining near freezing.

 

[Kantaro]

- For PFI engines, it's not really a necessity by any means. It can help but the improvements would be much smaller relative to DI systems.

Agreed. Why add another service item and risk restrictive or frozen lines for little to no benefit?

I only added one to my BMW because oil ingress in the intake eventually kills the very expensive DISA valves.

 

[2strokeNorthstar]

Unless the car has known issues you are introducing a new potential problem.

 

[wtd]

We run them on our 2007 Mustang GT, 2014 Mustang GT, and 2017 F150 with the 5.0L When the 07 Mustang was fairly new it was blowing blue smoke out the pipes on startup. We put a catch can on it and it stopped doing that. When I first pulled the tube off of the intake from the valve cover, there was tons of oil pooled in the line.