Given the improvements in modern oils, will a properly maintained road draft tube-based crankcase ventilation system still result in a sludged-up crankcase?

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

I agree that todays oils help a lot but without a closed system my car even with a new engine smelled when I pulled into the garage. I’d does not now with one..
There was no sludge build up in the 50-60’s on properly serviced vehicles including the Fords. Many saw 200,000 miles before needed it anything because they were driven, idled very little, and when driven it was not short trips which killed most of them. Today you must search for non detergent oil; back then it was the most prevalent. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.

FYI  I have had my 55 Tbird for about four years.  It came to me totally stock except for a 12 volt conversion. The road draft tube was left as built by Ford.  The engine that was in the car when I purchased it was junk, so I built a new engine. My new engine is by far the best Y-Block I have ever had and I have had a few. Despite this, my Tbird stunk up my garage when I would drive it back in. I got the message whenever I came home in the TBird and saw my wife running around the house opening the windows. I also had a few mysterious oil leaks which I chalked up to Y-Block 50s engineering.  Last year, I installed a PCV system from Casco to replace the road draft tube. This instantly fixed the smell problem and reduced my oil leaks substantially. Interestingly enough, my engine seems to idle better with the PCV too.  I check my valve adjustment frequently and the inside of my engine still looks like new, at least under the valve covers.

My two cents worth.

Sludge or prematurely dirty oil is still a problem with todays’ oil.  The quality of the oil is just one consideration as some oils fight that problem better than others. Other considerations are the engine temperature, the climate in which the engine is operated, the frequency of the oil changes, and driving habits or how the engines are run.  Failure to use a thermostat and/or using 160°F thermostats are not helping to keep the sludge formation at bay.  Hotter engines do a better job in burning off those contaminants that contribute to sludge forming.  Abnormally cool or high humidity temperature environments mandate a longer engine operation to get those engines hot enough to keep the oil somewhat cleaner longer.  Those short hops where the engines do not get adequated heated and/or just barely get up to temperature are high on the list for sludge formation regardless of the quality of oil being used.

The number one culprit regarding sludge formation still remains to be the oil change frequency for keeping the engine internals clean.  Not all engine oil is equal when it comes to the oil change frequency.  Some oils just do a better job of keeping the engines cleaner longer in regards to the oil change frequency.  More than using hours or miles for determining when to change the oil, the overall length of time is still a major consideration when determining how long oil stays in an engine.  As oil ages, it oxidizes and that in itself increases its propensity for forming sludge.

My ’55 with over 300K miles has had the oil changed each 2000 miles or once a year since 1989.  Initially it was every 2K miles but now it just occurs once per year.  The first 112K miles on that car had the oil changed at 1000 mile intervals which was probably to the extreme side but when I had the engine apart to upgrade the heads for unleaded fuel, it was literally spotless with minimal wear indicated if indicated at all.  The only thing wearing out prematurely with frequent oil changes would be the oil drain plug threads.  So far, those original oil drain plug threads are holding up just fine.

Lorena, Texas (South of Waco)

Thank you for your responses. My takeaway is that a road draft tube can be just fine for crankcase ventilation if oil is changed often enough and one doesn’t mind the crankcase odors.

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

While an open system may produce slightly more power, the PVC sure seems to reduce the oil buildup on body exterior.
BTW: Regarding sludge:  Years of running diesel engine oil (before I got wise) at least eventually dissolved most of the visible valve gear’s 50s non-detergent buildup I had inherited.

6 VOLTS/POS. GRD. NW INDIANA

I have read some comments elsewhere about that oily buildup ending up in the intake tract and on the valves with PCV.  I certainly have seen it on the closed-system "dry" manifolds of modern cars, but with our wet manifolds, doesn't the fuel clean things up for the most part?

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

A properly installed PCV valve will not contribute to either excessive oil consumption or an oily buildup within the intake tracts and/or the valves in the older carbureted engines.  If this is indeed happening, then look for anything that is causing excessive blowby or an incorrect installation or placement of the PCV valve.  Oil seepage within the valve guides would be at the top of the list for items to look at if deposits on the valves becomes problematic.

I have run engines on the dyno with the PCV valve hooked up versus not and there is no power difference either way.  In confirmation of this, I have dyno tested customers NHRA stock engines and they do run and race their cars with the PCV valves being operational.

Lorena, Texas (South of Waco)

56 Vic, B'Ville 200 MPH Club Member, So Cal.

6 VOLTS/POS. GRD. NW INDIANA