I check my catch can about once every year or so and have never had more than just a small amount of oil in it. Never had foam like that.
oil catch can content
Burning Brakes
Joined: Sep 2008
Posts: 866
Likes: 4
From: Bucks County PA
A couple of years ago I posted the question What's in my catch can? I had something very similar in my catch can. I haven't been concerned about it since.
Safety Car
Joined: Apr 2004
Posts: 3,532
Likes: 79
From: pueblo co
to the OP based on your mounting location which nothing is wrong with it at all imo, but could water be seeping in around the top part of the fitting and mixing with the oil?? i.e. water setting on top of the catch can and somehow seeps past the fitting into the can? would not take much to cause that ...just food for thought if at all even poss.
Race Director
Joined: Mar 2003
Posts: 10,789
Likes: 894
From: Northern Illinois
Oldtimer
Acct Suspended APR 2026 by request
Joined: Dec 2010
Posts: 10,367
Likes: 1,272
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
looks fine to me, I ran a catch can for about 3 years and it always looked like that... I have it vented to atmosphere now and no pcv system and when I drain the breather it's basically like water with an oil/gas smell to it
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Drifting
Joined: Mar 2014
Posts: 1,823
Likes: 757
From: Marysville Washington
This buildup shows up every year I do my winter oil change.
When you let a C5 sit for a month or so, and then putz around town a bit, the condensation goes to the top when you heat cycle, causing this effect on the oil in the area. I just did my oil change for the winter last weekend myself, and I had this under the cap. I pulled the valve cover, and everything was fine; infact, cleanest internals I have ever seen for a car about to roll over 98K. The same can happen in your catch can.
Make sure your PCV valve is free breathing, and take it out for a mean run for an hour or so once it's hot. If the milky concoction continues to come back, then it's time to start performing some tests.
IF I WERE YOU, in the interim, I would pop my throttle body off and have a peek in the intake manifold. I would probably even change the oil for cheap insurance. If it persists, I would do a compression, and leak down test, and open the coolant cap when you do the leak down so you can hear if the compressed air is making it's way into the coolant passages somewhere.
When you let a C5 sit for a month or so, and then putz around town a bit, the condensation goes to the top when you heat cycle, causing this effect on the oil in the area. I just did my oil change for the winter last weekend myself, and I had this under the cap. I pulled the valve cover, and everything was fine; infact, cleanest internals I have ever seen for a car about to roll over 98K. The same can happen in your catch can.
Make sure your PCV valve is free breathing, and take it out for a mean run for an hour or so once it's hot. If the milky concoction continues to come back, then it's time to start performing some tests.
IF I WERE YOU, in the interim, I would pop my throttle body off and have a peek in the intake manifold. I would probably even change the oil for cheap insurance. If it persists, I would do a compression, and leak down test, and open the coolant cap when you do the leak down so you can hear if the compressed air is making it's way into the coolant passages somewhere.
Last edited by ErikwithAK01; Jan 22, 2018 at 04:07 AM.
Burning Brakes
Joined: Jan 2006
Posts: 788
Likes: 105
From: Olathe Kansas
The Content is absolutely normal.. It's moisture, fuel, Crap, Oil All mixed up ..
I have a vacuum pump on my 422 ci SBC and get out way more junk than just that..
Just remember, It's crap that is NOT going back into your intake/ engine/ Oil ...
So it's a good thing. It's doing exactly what it/s intended..
If you are not having to add oil or coolant.. Then No worries..
As a side note: The DIC oil change interval is not always the best guide.. change it
way more often..
I have a vacuum pump on my 422 ci SBC and get out way more junk than just that..
Just remember, It's crap that is NOT going back into your intake/ engine/ Oil ...
So it's a good thing. It's doing exactly what it/s intended..
If you are not having to add oil or coolant.. Then No worries..
As a side note: The DIC oil change interval is not always the best guide.. change it
way more often..
Supporting Vendor
Joined: Aug 2013
Posts: 1,375
Likes: 303
From: Virginia
looks delicious!
also check that the pcv front line (either to top of tb or to air bridge) is not blowing oil forward of the throttle blade. this happens as the engine wears, during long periods of aggressive driving, or as power increases.
if it is then this oil your current setup is not addressing.
also check that the pcv front line (either to top of tb or to air bridge) is not blowing oil forward of the throttle blade. this happens as the engine wears, during long periods of aggressive driving, or as power increases.
if it is then this oil your current setup is not addressing.
__________________
Solutions for the common gearhead #made in USA
mightymousesolutions.com
facebok.com/mightymousesolutions
#mmsolutions
Six time NMCA True Street Champions
Home of the first Twin Turbo C7Z 7.81 @ 176
3470# Stock bottom end and heads Corvette Stock Bottom End Record Holder
Solutions for the common gearhead #made in USA
mightymousesolutions.com
facebok.com/mightymousesolutions
#mmsolutions
Six time NMCA True Street Champions
Home of the first Twin Turbo C7Z 7.81 @ 176
3470# Stock bottom end and heads Corvette Stock Bottom End Record Holder
Miles of Smiles
Joined: Mar 2010
Posts: 3,180
Likes: 559
From: Omaha Nebraska
2016 C5 of the Year Finalist