How much blow by is too much?

[Ramnation]

I've been watching my catch can for the past month or so, I religiously change my oil around 5-7k with 5w20 synthetic with the larger viper or hellcat filter, I dont believe in the 16,000km oilchange interval bs the manual suggests. I recently installed a custom catch can and I'm getting around 175mL blowby every oil change , seems a bit much, I feel bad for the guys who go 16k or 1 year with no catch can... I have a feeling this is because if people maintain like me the engines wouldn't wear down and that's not good for sales? Call me crazy?

 

[whetrick1]

I've been watching my catch can for the past month or so, I religiously change my oil around 5-7k with 5w20 synthetic with the larger viper or hellcat filter, I dont believe in the 16,000km oilchange interval bs the manual suggests. I recently installed a custom catch can and I'm getting around 175mL blowby every oil change , seems a bit much, I feel bad for the guys who go 16k or 1 year with no catch can... I have a feeling this is because if people maintain like me the engines wouldn't wear down and that's not good for sales? Call me crazy?

No probably about right. I dump mine every 2000 to 2500 miles. And I usually get about 3 OZ. Out of it. I think every Hemi is going to be a little different. Do yourself a favor and put a drain valve in it and it makes it alot easier.


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[Ramnation]

No probably about right. I dump mine every 2000 to 2500 miles. And I usually get about 3 OZ. Out of it. I think every Hemi is going to be a little different. Do yourself a favor and put a drain valve in it and it makes it alot easier.


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I wonder why they wouldn't install a catch can from the factory knowing these hemi's push so much oil back into the intake, I'd love to see 100,000 mile comparison with and without catch can results

 

[whetrick1]

I wonder why they wouldn't install a catch can from the factory knowing these hemi's push so much oil back into the intake, I'd love to see 100,000 mile comparison with and without catch can results

I asked my service manager the same question and he told me that most people wouldn't check it and it would get full and start dumping into the intake.


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[bigwhttrk19dt]

What is the recommended brand of aftermarket catch can for a 2019 Ram with the 5.7L Hemi ? It appears the Mishimoto is a simple bolt-on to the radiator support/shroud, however I do see some that have an attachment point on the right front ( passenger side ) of the engine. Comments & recommendations sincerely appreciated. Thank you.

 

[cra1g]

I asked my service manager the same question and he told me that most people wouldn't check it and it would get full and start dumping into the intake.


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Or...maybe because it doesn't actually hurt anything?

If you dropped 3oz of oil in your driveway, then washed it away with 120 gallons of gas, would you expect any trace of the oil to still be there? Because that's what's going on in your engine every 2000 miles.

 

[whetrick1]

Or...maybe because it doesn't actually hurt anything?

If you dropped 3oz of oil in your driveway, then washed it away with 120 gallons of gas, would you expect any trace of the oil to still be there? Because that's what's going on in your engine every 2000 miles.

Or if you dump alot of oil in your intake everything starts to sludge up. Everyone has their own opinion about it.


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[Scram1500]

If this was a direct injection engine it would be more of a problem, but the injectors on the hemi wash down the intake valves and any deposits. That being said, a Mishimito is the next upgrade on order. That stuff doesn't belong in the intake, it used to vent to the atmosphere

 

[jkm312]

This truck engine is the first time I've used a catch can, Mishimito. Put it on with less than 300 miles on the engine. I dump it at every oil change, 3000 miles and again 1/2 thru an oil change. Got the truck mid March 2019. Last oil change was mid Nov before winter set in for real. What I found in the can this past weekend was more water condensation than usual. Cold weather and short drives for me, small town. Why would you let that gunk go thru an engine if you have another choice, which I do? Yes it's one more thing to keep track of, but then why not?

 

[warmmilk]

Or...maybe because it doesn't actually hurt anything?

If you dropped 3oz of oil in your driveway, then washed it away with 120 gallons of gas, would you expect any trace of the oil to still be there? Because that's what's going on in your engine every 2000 miles.

it gets oil all over your intake system and oil reduces octane of your fuel... its not a huge deal but I like to get the octane I paid for.

another thing to keep in mind is not all catch cans are created equally... a cheap one can collect oil and still also let oil in through the intake system. Here's a vid (sorry about the ford content) that illustrates my point:

 

[Joshohol]

I installed a mishimoto the other day on my truck. I know in the past on my cars when my catch can freezes in the winter it screws everything up and dumps oil like crazy and smokes. Same thing on these trucks or does the pcv bypass?

 

[Nails]

The main point is not intake valves gunking up on hemis. It has been shown to add up over time in combustion chamber. Over time, shown to change A/F ratio and fuel trims and adds knock(pinging). Which all relate to less efficient and power output.

 

[cra1g]

The main point is not intake valves gunking up on hemis. It has been shown to add up over time in combustion chamber. Over time, shown to change A/F ratio and fuel trims and adds knock(pinging). Which all relate to less efficient and power output.

OK, but by how much and after how long? If we're talking 2mpg after 10k miles, that's a big deal, and worth doing something about. If we're talking .001mpg after 300k miles, then who cares?

 

[Nails]

OK, but by how much and after how long? If we're talking 2mpg after 10k miles, that's a big deal, and worth doing something about. If we're talking .001mpg after 300k miles, then who cares?

I don’t disagree with that. There are many that have said no issues at xxx,xxx mileage. That’s awesome, no mechanical issues. Yet I’ve never heard talk about how the mileage still is same, Ect. Or how it’s had volumetric/fuel trim efficiency tests done after break in then at that end point? No just that it’s still running fine. CC is for maximizing combustion event/keeping combustion chamber clear of contaminated oil, which will help avoid mechanical failures as a side plus.
It’s a tool, just like people putting a additive in the tank every x fill ups/miles.
I get it and understand that the less money put into maintenance and still a great result of engine still works. I’m not bashing that. That doesn’t mean there wasn’t degrading of efficiency & fuel mileage. It’s a slow process, the fast pace world we live in it’s easily over looked.

Honest true answer would be 30-50k is starting to degrade and become less efficient. Definitely 50k at the same, still so many variables to add or subtract miles from that.

 

[Joshohol]

I mean I come from direct injected vehicles where carbon buildup is an issue. I couldnt see there being build up when they valves are covered in fuel everyday as engines always have been. I only got a can because I saw people were running them and the 2nd day of owning I pulled the throttle body and saw oil.

 

[Orion10182011]

I mean I come from direct injected vehicles where carbon buildup is an issue. I couldnt see there being build up when they valves are covered in fuel everyday as engines always have been. I only got a can because I saw people were running them and the 2nd day of owning I pulled the throttle body and saw oil.

It won't build up on the intake valves of the HEMI like a GDI engine will. But a catch can is still a good thing as long as you maintain it. I put a new intake manifold on my Corvette C6 (port injected LS2) and the old intake was full of crap from the PCV system. Yes you could see it was perfectly clean where the fuel injectors spray constantly but the rest of the intake ports were black as coal. Keeping that oil out of your engine is a good thing. Should help with carbon build up on the combustion chamber and the head of the pistons too. And like someone said above oil from the PCV system reduces octain tolerance of the engine.

That experience led to my buying a catch can for the Vette. Now that I have a Ram I've added one to it as well.

 

[gHiDoRa]

Quick question, how do we clean the oil catch can? What should we use to clean it?

 

[YellowSled]

Quick question, how do we clean the oil catch can? What should we use to clean it?

pour it out?

 

[gHiDoRa]

pour it out?

LOL, i know that part, i'm talking about the top part where is filter/catch the oil.

 

[Scram1500]

LOL, i know that part, i'm talking about the top part where is filter/catch the oil.

The sintered brass filter nut? I don't think that needs cleaning but gasoline would be a good solvent