View Full Version : Oil separators?

09-30-2015, 06:25 PM
This is a gizmo (in black or aluminum finish) that is aimed at new Mustang V-8s:


It is an oil separator that goes on the hose going to the pvc valve. It is supposed to keep the intake manifold clean.

See: http://www.cjponyparts.com/jlt-oil-separator-passenger-side-kit-gt-2011-2015-boss-302-2012-2013/p/OILSEP4-V/

"Easily one of JLT Performance's most popular products, their oil separator will help keep oil out of your intake. While your engine is in the process of venting crankcase pressure back through your intake track, large amounts of oil, in the form of vapors, can coat your intake runners, throttle body and even dilute your gas, lowering its octane level. And a lower octane rating means less power!"

If it is a LARGE amount of oil, maybe it would be a problem, but the engine would be having problems anyway. This product is being promoted as something to put on a new car.

Is there any point to that? Do any of you use one of these?

I know that my 260 V-8 has some steel mesh upstream of the pvc valve that is supposed to catch oil droplets. Does the new Mustang V-8 not have anything like that, making an aftermarket oil separator necessary?

10-01-2015, 10:44 AM
Anything to make a buck. But, maybe not.

I think, if you're seeing enough oil to "catch" in something, the engine is installed upside down.


Vaporized hydrocarbons coming from blow-by and what-not will burn off pretty good. It may smoke as well, but I'd not be too worried about the intake runners getting 'choked off' by this. The worse case is when someone feeds the PCV to only one intake runner and only that cylinder is asked to burn it. Fouled plugs are also a result. But this is on an already worn engine, usually.

I suspect, though, if it is a mesh-like thing similar to what you have, it may trap anything that can attach itself to the mesh. If it were user cleanable (like a K&N filter), you may negate some smoke out the tailpipe and not get dinged with perpetual filter costs. If it were any tighter than this, as something to create a pressure drop in the line, I'd be concerned about it allowing the PCV to do what it was made to do.

That said, of course, the motor will run just fine without a PCV valve too as long as there are vented breather caps.

All of this may not be as true with new motors with cams in the heads near the place where a PCV tube may be. These may atomize oil droplets more-so than a rocker arm will. But I'm not up much on these newer systems.

I know on later 70's/80's model engines, which had a tube running from the oil filler cap to the intake, these had a mesh "filter" on the inside of the air cleaner that always gooped up with oil. Clearly sucking it up the tube.

So, you be the judge. It may be a cool-looking add-on and they'll make a buck!

10-02-2015, 04:55 PM
Hello, Roger.

I thought about the oil separator idea and read about it further. For most cars, you will not accumulate oil inside the intake manifold because the carburetor or fuel injection is blowing a gasoline mist through the same intake. The gasoline is constantly washing away any oil.

But, .... there is a new version of fuel injection called "direct injection" that injects the gasoline directly into the cylinder. There is no gasoline vapor washing through the intake manifold. The new Ford EcoBoost four cylinder engines use direct injection. In that case, the oil separator "might" be beneficial. Otherwise, it is difficult to find any point to it.

"Direct Injection: The second part of Ford's EcoBoost engine is gasoline direct injection, or simply direct injection. Direct injection is one form of fuel injection, which is the process used to send fuel into an engine. While typical fuel injection uses an extra step known as the intake tract to inject fuel, direct injection cuts out that process entirely. The result is a less complicated fuel injection process, which improves efficiency."

See: http://www.autotrader.com/car-tech/ford-ecoboost-what-is-it-and-do-you-need-it-210645

10-02-2015, 06:57 PM

My Kia and many other cars use GDI engines (Gasoline Direct Injection). My Kia is pretty peppy for being 2.0 litre and my GF's car has the same motor, but turbocharged making close to 300HP. I found the following web page talking about this:


The paragraph I found most interesting, as it relates to this thread, is this:

Due to modern unburned hydrocarbon (UHC) regulations, vapors from the crankcase are usually vented into the intake stream in order to prevent oil droplets from escaping through the exhaust. In a port injection engine, these droplets are ‘washed off’ the neck of the intake valve by a relatively constant stream of gasoline droplets. In a GDI engine, the gasoline doesn’t touch intake side of the valve. As a result, the droplets have a tendency to bake onto the valve and significantly reduce performance. To add to this effect, many advanced GDI engines also include exhaust gas recirculation in order to lean out the combustion mixture and reduce in-cylinder temperatures for certain combustion modes (reducing NOx emissions). Since GDI combustion has the ability to produce far more soot than premixed combustion (port injection), the problem is magnified.

Even more alarming is that these deposits can dislodge and damage other downstream components (turbochargers, catalytic converters, etc.). Manufacturers have added systems to capture these oil droplets and particulates, but no system is 100% effective.

So, it seems, this little filter is pretty important... on this type of motor at least.