It's now using over a quart every 1k miles. I had to get rid of a car that did the same thing and here I am tackling it again.
It does have a lot of miles (191k) but runs great. I do not notice any smoke, have already replaced the valve cover gaskets because they were leaking into the spark plug holes. I don't have a compression checker. I have taken the pcv hose off and the car stumbled big time. MPG doesn't seem to be down and no leaks.
but I'm wondering if there's a special test I can do without spending what looks like over $300 on a valve cover for this car.

 

Couple of things can affect oil consumption. I'll offer these up first...

1) Run the right oil. Modern oils are high detergent which helps keep the engine free of sludge but a side effect is the oil tends to foam/aerate more. But the proper high detergent oil will have additives to address this.

2) Don't overfill the engine with oil. Overhead cam engines already generate copious amounts of oil vapor. And if the engine is turbo-charged this results in more blow-by and this just adds to the load of "stuff" that makes up this vaporous atmosphere in an engine crankcase. Overfilling can only make this worse.

3) Don't run the oil too long. As oil accumulates miles it gets contaminated. Among other things this leads to more oil vapor forming and more vapor means the air/oil separator which may just be some fancy baffling in the valve cover has more work to do. If it is not every effective at removing the oil vapor oil consumption can increase.

4) How you drive can affect oil consumption. Lots of idling or lots of high RPMs increase oil consumption.

One quart every 1K miles is not that severe of oil consumption. Granted it is towards the high end of oil consumption but enough to fret over? Especially if the engine is running ok and not smoking?

Rule #1 is if it ain't broke, don't fix it.

For some engines that have a problematic air/oil separator (AOS) -- engines I'm most familar with like Porsche, the one in my Boxster -- the AOS can fail.

In an attempt to identify a bad AOS before it failed "catastrophically" (passing so much oil vapor (or oil droplets) on to the engine the engine was smoking like a Chinese coal burnng power plant) what was devised is a test to measure the air pressure inside the crankcase. An engine at idle with a healthy AOS should show around 5 inches of vacuum. (A slack tube nanometer is used to measure the pressure (low pressure) in the crankcase.)

'course assuming this "test" is even valid for the Mini -- it should be the principle is the same but of course I'm not a qualified Mini technician -- I don't have a number for the Mini. But if you have access to any other Mini's with an obliging owner you could measure the vacuum/pressure and develop some kind of baseline. Probably.

A lot of work that will probably have you realizing your car's crankcase ventilation system is working about the same as others.

There are probably no moving/serviceable parts in the crankcase ventilation portion of the valve cover -- with other engines this is just some baffling -- so even if you bought a new one there is a chance due to manufacturing differences it may work the same or possibly be even worse.

Now if there is a PCV valve this may go bad -- years ago I was taught if when removed the valve rattled when shaken it was "ok"but that was back when these systems are simpler ( have to add a new PCV was so inexpensive if the old one was suspect, or even it it was not, SOP was to just replace it with a new one ) -- and if it has become unable to properly regulate the amount of vacuum the engine is subjected to this can result in much too vigorous air flow through the valve cover vapor recovery system with a corresponding increase in oil consumption.

If there is a separate PCV you might throw a new one at the engine and see what effect, if any, a new PCV has on oil consumption. (Save the old one if the new one proves to be worse...)

Getting a bit more involved, there might (might) be a modification you could do to the existing valve cover baffling to improve its function. You would be attempting to improve on the factory's design and I dare say you will probably not succeed. At the same time this brings some risk. If you add some extra baffling if this baffling comes loose, even if a screw comes loose, guess where it goes? Yep. Right in the valve train hardware. Ouch.

Frankly even though I put this out there I would advise you to forget about it...

For some engines owners fit an oil catch can. This is not done to address excessive oil consumptiom but to reduce the amount of oil that is routed to the engine (oil in the intake charge can to some extent negate the benefits of octane in premium gasoline and this can lower the threshold at which detonation can occur and spark is retarded to address detonation but this lowers the engine's output). While some oil is removed/caught that the crankcase ventilation system is routing to the engine not all oil is caught. Reports are there is still signs of oil vapor reaching the intake manifold walls. In most cases just a few ounces of oil is collected over several thousand miles. Thus a catch can is a "solution" to a non-existing problem really. (And really, a few ounces over several thousand miles is not going to have any measurable effect on engine performance.)

 

thanks for the well thought out response sir.

#1 I use Castrol GTX High Mileage 5w-30 blend. That is a very fair oil for this car.

#2 The dipstick is stupid but I don't believe I am overfilling it. I'm with you on the OHC explanation. That did happen once with this car and the car told me. (oil cap was bad too at the same time)

#3 I am well within my interval at the moment. Besides, with the oil I have to add, wouldn't that negate this somewhat?

#4 I don't beat on this car. 4k is typically as high as it gets.

I'd be inclined to know if there is an air/oil separator, but something tells me that would only come on the S models.
Anyone with a base model want to chime in on adding a catch can to this car?

 

At 191K I'd suspect piston rings and valve guides. A compression test and leakdown test will tell you if you have any issues. You're not getting any smoke because the oil is getting burned up in the engine and in the catalytic converter. Too much oil in the cat will eventually kill it.

 

I recommend doing a leak down test. My Mini engine was consuming oil around 550 miles per quart. It didn't smoke, ran fine and was getting great gas mileage. I check my oil every week and top it off, changed it every 5,000 miles, installed an oil catch can and eventually changed the valve cover. After testing each cylinder, the leak down test clearly shown the rings were bad. Now a new Mini engine sit between the wheels.

 

We have a similar discussion going here: https://www.northamericanmotoring.co...on-issues.html

Start from the last page.

One of the culprits is the PCV or CCV that is built into the valve cover piece. I balked at replacing it for about $350 until I saw a post for the CCV itself for just $30, which took a month to arrive from Russia. It cost another $30 to install (or DIY).
Others have said this part fixed the excess consumption; mine has only been installed for a week- still testing its effectiveness.
I found the part on eBay searching N12 CCV, etc.


Here it is just installed with the retired OEM next to it.