Another Oil-Catch Can Install (moroso) - with Pics & theory.

I think you may be on to something with that fine mesh. Its amazing how much internet stuff exists where people tell you how OCC's work, but they dont actually tell you how they work - like in terms of scientific/engineering principles. Seems like maybe trade secrets or simply general lack of knowledge. Where is a good mechanical or chemical engineer when you need one!

Seems like maybe the oil "vapor" is not really vapor, but actually a fine mist which is already liquid just sloshing around in the air. I'm leery of those nickel-sized brass-pore filter OCC's, but I did some more research and found a foreign OCC invented by some German guy. The company is based on Australia now, but they make cans for diesel intercoolers and big trucks.Their mesh filter probably has a surface area of about 15-25 sq inches.

Catch Can Pro - Genuine Flashlube™

Video of some good'ole ausie mechanics, who seemed to know what they were talking about - talking about the flashlube filter:

Allan Gray 'Catch Can This' - Roothy Bushmechanic - YouTube

I emailed the company to see if they could offer a cheap demo to me.

Regarding the better gas mileage and more power with less oil in the air comment: in one of the Aussie videos, the guys mentioned that as well: less oil in the intake = noticeable more power. Probably slight but maybe noticeable to a very keen/aware driver.

 

Continuing on with the Oil-can research project today. Wanted to share a few blurbs and info.

1. My moroso is catching stuff, half water, half oil, or something in between. the can doesn't seem to be sealing well. Either the rubber o-ring gaskets dont work good enough, or my teflon tape job is bad. I'm going to tear apart and use some better tape in a day or so. I suspect the o-rings dont work well however since the "can" basically screws on without increasing gasket resistance, until it "bottoms out" on the metal can head itself. this tells me I might have plastic can on metal head contact, with no effective o-ring.

2. The can efficiency seems to be kind of crappy - but its still too early to tell. One nice quality indicator I found is to take a cute-tip cotton swap and wipe the outlet hose at the intake manifold side. if this is dirty, oil is definitely getting through - unless I'm missing something due to the funky atkinson cycle actually pushing oil up through the crankcase into the chamber and into the IM, due to valves partially open or something like that.

if we assume 2 is the simple issue - can just sucks - then more data is needed. My results (and some very rough analysis of other folks can collection rates) suggest somewhere between 10-25% oil catch efficiency. But i dont have enough data yet. If the numbers are true, my solution, and most of the other cans out there, probably suck and are just delaying this problem in a minor way. Luckily, I found diesel-heads probably hit this problem and there is quite a bit of research on this topic. Dirty diesels and their inter-coolers have the same essential problem, but its more noticeable earlier on and more expensive to fix when it becomes a problem.

I never got a reply from Flash-lube, so they kind of suck as a company. More digging through the internet resulted in this YT video from an Australian guy who started with an HPD OCC (similar in design to a Moroso), found it wasn't working as good as expected on his Toyota SUV:

and he dug deeper, found this paper, which I'm trying to get my hands on. An actual scientific study of OCC's - amazing, it exists. Thank you SAE! I guess that logo on every bottle of oil actually means something! LOL

FlexPaper AdaptiveUI JSP Example

The paper is available free as a digital download after you create an SAE account. the "good" can is the provent, and labeled CF2.1 on the graphs. the "bad" can, similar to the moroso, is labelled CC1. the quality/efficiency numbers difference is striking!

Anyway, paper shows quite a difference in efficiency and airflow blockage among different vendors and Can essential designs (mesh versus wool, etc.). I also found some videos, showing a a removed OCC cap while engine running; and basically what you see is Oil mist boiling off the can, similar to a cauldron of water just before it reaches boiling ("smoke" on the water, in essence). That's a pretty telling sign that this stuff is definitely a mist and not vapor.

Some more general scouring on the internet shows that a decent diesel engine with a 100% theoretical OCC catch, might yield around 1oz per 1000 miles. This is very rough, but that's about 1 qt per 32000 miles. Or put another way, after 100k miles, you essentially burned 3 qts of oil through your engine. If flow rates through PCV are similar between diesel and gas ICE, then that's what we can expect through our Prius. This seems reasonable and would explain the very gradual onset of this problem.

Now I'm just some dumb guy who knows how to search the internet, but I'm starting to wonder why a trained, highly-paid auto engineer at Toyota, or any car manufacturer for that matter, hasn't designed in a 90%+ efficient OCC on every freaking car made, which has a PCV routing to the intake manifold - hasn't oil burning been a problem on high mileage cars since forever!?!?!. NOTE: some research shows there might be some sort of crankcase OCC built into most Toyota engines. this is visible in some tear down videos, but if its there, it hasn't been well designed, or at least not designed well enough. With a Prius, you are either a cheapskate or environmentally concerned. this means you probably want 250k+ miles out of your car and you dont like polluting the atmosphere with burned oil. Whenever you optimize a system, the next weakest link is exposed. I'm thinking the built-in OCC/PCV is that sub-system on the Gen3 Prius. Here is another white paper from Mann+Hummel, which indicates lower oil viscosity is causing increased problems for conventional mist separators, as the oil mist is becoming smaller, approaching the size of the air molecules in the mixture, making deflection style separators not as efficient.

Whitepaper_CCV_V1-1.pdf (mann-hummel.com)

I think the built-in Toyota OCC is an oil deflection type baffle system. This below link from a honda research paper shows there is quite a variability in efficiency in the baffled built-in OCC's. So essentially, it's probably very easy to screw up, especially if you design an engine for higher viscosity oil and then change the spec to something lower viscosity:

https://enginsoftusa.com/pdfs/Honda-Engine-CFD-Particle-Method-Analysis.pdf

I'll probably procure and install a MANN+HUMMEL ProVent OCC on my Prius in the next few weeks. But wanted to get this info to the group for any feedback. That would definitely be most excellent if we could solve this problem in a 90%+ way. Imagine if we could find the holy grail that kept these Gen3 engines soot/gunk free for 250k+ miles in a definitive way! I think Toyota may even start to listen and read these posts - if that were the case! Even with a good OCI at 5k, and quality oil, it seems like something else might be needed.

Happy "Black" Friday - literally!

QUESTION FOR THE GROUP: what is the max PCV valve system flow rate in L/Min of air, on Gen3 Prius? This is important is sizing these Mesh-style filters.

 

exactly my thoughts. im in the process of procuring a provent 100. the size is apparently suitable for our prius. the provent model numbers are confusing and they are switching to a gen2 version of the can in summer of 2022, making the gen1 can hard to find. I bought one last week, but the store was out of stock. So im now going to one of those Chinese knock-offs. im anxious to test it. Initial numbers i glued together showed that it should be more efficient than the moroso - at least in first swath of data. this isnt the panacea for the gen3 oil burning problem and am still working on that one too. but i think a good working can will be a start! Side Note: the Provent cans are very big! Its going to be a stretch to even get the v100 mounted into the engine bay. I dont think the 200 will ever fit.

 

Putting the PCV valve there makes the run to the IM very short, hot and easy. Maybe they wanted to keep those gases nice and hot so they might burn better, instead of condensing all over the hose and IM.

Check out this video at 11:25, showing the oil separator plate. Not the exact same engine, but i would bet that behind that bolt on PCV plate on G3 Prius is the oil separator assembly, similar to what shown here:

Here's Why Toyota Engines Consume Oil. Tear down and Repair. - YouTube

the only problem is that it doesn't appear to work well enough. But for this reason, moving the PCV valve may cause ill-effects. We need someone to remove that plate and see whats in there!

Some research suggests these oil-separators are merely impaction devices, catching only the amount of oil that drops out due to impacting the plates at high velocity. Considering this, its a wonder, the IM isn't clogged at 20K to me; so it seems to be working pretty well actually, just not well enough for Prius owners, who more than average person, probably want a 200k-250k mile car! Honda research published a paper showing how a minor difference in plate spacing caused a major amount of oil mist to pass through the separator.

My current theory is maybe the switch to lower weight oil on G3 (0w-20) from G2 (5w-30??) coupled with the extra soot from EGR, means more pollution in the G3 intake. This causes more wear sooner. Still searching though and may never have an answer. I know there are 2-3 engineers at Toyota who know where all the oil burning "dead-bodies" are with this car. When you design something and test the crap out of it before production, as an engineer, you may not be able to quantify the short-comings during the design phase, but you can have hunches, and can definitely say "I told you so" many years later after management rushed the product out the door. Where are those guys? Why dont they chime in on these forums? Baffles me. Wondering if they even read these things. I would if I was designing Prius Gen4!

 

hi Nate, here is a little update with some pictures. After studying this, I believe the Provent 100 or mesh style filters will do a much better job than the typical top-down air flow cans like the Moroso, or the common ones bought on amazon. In fact, after some measurement of oil lost after 1500-2500 miles (using the dipstick drop method),and measuring how much oil has been caught in the moroso installed in the 2010 prius, im fairly convinced the typical OCC's are almost worthless. I estimate, I'm catching at best 15% of the lost oil, and its probably down under 10% effective catch rate. And that's assuming all the junk caught is oil, which is doubtful, since there is usually an oil-water type separation layer in my OCC when I drain it.

Having measured this, I gave it a good college try to acquire and install the Provent 100. I procured a few of them from Alibaba (stainless and plastic mesh filter options). These things are quite difficult to get in USA and very scarce even in Germany. Apparently, Mann is switching to a new style but don't have it ready for sale, and the old ones are limited in stock. The ones I got from Alibaba were a bit sketchy in quality in my opinion, and considering China is known for fake things, i presumed these might be fake. Also, there are two styles of overflow venting: one where the vent shoots the "air" out of the OCC into the engine bay and the other where the overflow opens a passageway to just shoot the overflow back into the intake - less messy. I got the first kind because of part number confusion, and I couldn't locate the latter. So, I didn't really want to deal with oil-gunk-air in the engine bay.

Anyway, I have these things, but the fit is quite tough. I'm attaching some pictures, near the invertor-headlight, where i might install it. on the 2013, there is a grounding strap on the invertor. I'm pointing to it in the pictures. that is prohibitive. on the 2010, i could probably swing it, but the tube routing would be a mess. additionally, I would have to adapt down some 5/8" OD tubing ports on the provent, which is another pain in the arse.

Long-story-short, I kind of got side-tracked with work and about 5 other projects and just left the moroso in the 2010, since I didn't want to pull it quite yet. I have these provents if anyone wants them to give it a try. I can ship/send to you for a nominal amount. I would be interested to see some results. one has a stainless mesh filter. the other has a plastic mesh filter.

Not being an automotive engineer by trade, I have to admit, I'm kind of burnt out on this oil-burning garbage project, which Toyota has inflicted us with - especially considering I bought my two Prius expecting to get 250k out of each one - with the expectation of replacing the traction battery after 10+ years or so. I have a 2010 (145k) and 2013 (70k) and have been generally quite pleased with the cars. In fact, the 2010 still has a strong traction battery, looks practically new - well maintained, and washed though! If it had a new engine, and traction battery, I could load it up with some new struts and it would probably go another 150k with minor work. The 2010 is still pretty okay, burning maybe less than .75qt every 4-5k miles. the 2013 is still not burning much oil at all. I may try a heavier weight oil at my next OC, starting with the 2010 as the experimental car.

So far my best solution to this mess has been to invest in an e-bike and keep the prius in the garage as much as possible! I live in Portland and am including a complimentary shot of my bike on a bridge backdropped by the union station. LOL. Hope that helps!!