How much oil in your catch can??

[therealmo]

Hey everyone,

I have a 2006 D22 STR 3.0L

I installed a provent catch can a few months ago. Didn't see a whole lot of oil getting filtered for a while.

I have since done EGR, intercooled and chipped with a steinbeauer and now it seems like i am filtering a shit tin of oil. It took 2 tanks of fuel to fill a 300mm length of hose off the bottom of the filter.

Is this normal?
Is this way too much?
What could be the problem?

How do i plumb the line back into the engine?

Cheers

 

[Old.Tony]

The EGR, chip etc might have something to do with it, but from the periphery.

The PCV line gets hot oil in it as a result of blow-by (combustion gasses passing by the piston rings into the crankcase). This pressurises the crankcase and the hot oil - made hotter by the combustion gases - forms a bit of mist and that is carried up through the PCV line, which is the only escape for it (since the dipstick has a seal on it to prevent oil mist from escaping).

More oil in the catch can means more blow-by and hotter combustion is occuring. The EGR mod is certainly responsible for higher combustion temps in the mid-RPM range and the chip will add fuel to the combustion process making it even worse.

That said, you'll find your economy is better with the EGR mod/chip/intercooler (if you drive for economy and not power) so undoing these mods may not be worthwhile. The additional price may be the extra oil in the catch can.

As for returning the oil to the crank - not something you could do while the engine was running, because of the positive crankcase pressure, but a one-way valve that opened when the crankcase pressure reduced to zero (engine off) allowing the oil to return automatically is a neat idea. I don't know if it's been done.

 

[tweak'e]

what could have happened is the filter has held the oil in itself and so there has been a delay before the oil has shown.

i get 200-300ml per 5000km's.

 

[therealmo]

So on that note if i just keep returning the oil to the engine she should be right?

Thanks, was getting a bit worried

 

[tweak'e]

either fit a bottle to catch the oil or plumb a return line back to the engine.
bottle is cheaper/easier but you have to remember to empty it.

 

[reddog]

What Tweak'e said

I also fitted the ProVent some time back and was geting nothing in the drain tube. When I had a look the oil was just collecting in the filter. It is really quite absorbant. Must have another look and see if it is now draining out of the can.

 

[Chris T]

very little oil

Just fitted a catch can home made design but same theory as all the rest filter material etc and in the last week have travelled from Toowoomba Qld to Darwin towing 1 tonne camper trailer a couple of 11hour runs and when I checked it this morning no more oil around turbo and about 5-10 ml of oil in the bottom of can which made me happy so how much oil is normal .Personally I would not return oil to the motor as oil is cheap .

 

[Old.Tony]

As long as that oil doesn't pick up any contaminants there's nothing wrong with it. It's oil vapour/mist that is pumped out of your crankcase by the blow-by gases that are hitting the rest of the oil anyway. It'll be just as good as the oil that wasn't turned to vapour - if you pull out your dipstick, you should see the oils are the same colour still. Just coming out of the PCV doesn't damage the oil in any way.

It's such a small amount, so it doesn't really matter either way. One thing that does change - if you're using a catch can and preventing the oil from entering the intake manifold, you no longer need to worry about the ash content of the oil, and rather than purchasing JASO-FD-rated oil (very expensive) you can get an oil that lubricates and cleans just as well, but may have a higher ash content.

The FD-rated oil is prescribed by Nissan BECAUSE it goes back in the intake manifold.