Oil consumption and white smoke on my Golf GTI mkV

[Work in progress: looks like it is the turbo (see all the way to bottom)]

Here is my post in the forum
Based on their replies, pointed me to the PCV (positive crank case ventilation) system.
How I checked it. (all you need Torx 25, a.k.a. T25, screwdriver, very simple). Another video with a bit more detail on how to test the valve once it is out. Note: When I see their hoses in the videos, they look really messed up with oil but mine were in that sense pretty clean.

Also, I saw the under-car splash engine shield with lots of oil. I don't know if that was because of the bad installation the oil shop did of the oil filter (so, something dirty from the past) or is it something new. But if that was the problem, my mechanic should have seen it when I brought it in, so, I don't think it was. Or maybe they thought it came all from the filter and there was a different problem? But recall that the oil guys told me I was very low and they didn't report any leaks. They did report a lot of sludge on the oil, which is a symptom of the blow-by mixing with the oil if the PCV does not work...

The valve costs $30-$55 in Autozone

Now, if you want to know how the PCV works in the GTI MkV, Howardc64 does a great job explaining that in this forum post. I copy it here in case they take the other one down one day. You may not understand all what is written the first time you read it (I didn't), so, I put some Youtube videos below that may help you with engine concepts, but I have to say that he did a very good job at explaining this:
"First, a quick explanation of blow by gasses and why all this vacuum stuff. When cylinder combustion occurs, some gasses will leak past the piston rings. This basically blows air into the crank case and need to be vented to prevent the pressure from pressing out of weak spots like oil seals. Crankcase has open air path to the head so common leak places are oil filler cap, cam seals and rear main seal depending on the different turbo engines. So how do we vent this pressure? On turbo cars, it needs 2 paths.

Path 1 is intake manifold when there is vacuum (pistons draws in air creating the vacuum). This vacuum will suck out the blow by pressure into the intake manifold and crankcase/head pressure will become negative or neutral. But what happens when turbo is boosting and pressurizing the air into intake manifold? There is no more vacuum so what do we do?

Path 2 is to vent this pressure to between the air filter and turbo. Usually just before the turbo. There isn't much vacuum here since air filter doesn't restrict much air to create high vacuum. But it is clearly a good place to dump excess blow by pressure.

On 2.0TFSi, path 1 is what is commonly referred to as the front PCV and path 2 is commonly referred to as rear PCV.

Path 1 has a check valve supposed to stop sending pressurized air into the head+crankcase whenever IM (intake manifold) is pressurized! The check valve suppose to close and relies on the path 2. This check valve in path 1 seems to have high failure rate. People use 2 solutions 1) add a stronger check valve (Digital Hippie Mod) or 2) choose to block off path 1 and just rely on path 2 (I think simpler and less failure) Lots of "PCV delete" kits out there for solution #2.

Now onto path 2. This is NOT a vacuum source. It is mostly a venting source. When turbo pulls in the air, there is plenty of air supplied from the air filter path. No huge vacuum will be created, maybe the tiniest. But you can certainly vent blow by gasses in here without any issue. And when venting, crank case pressure will be slightly positive but not enough to push past any oil seals so its fine. This path has to vent whenever IM is pressurized. Any check valve in this path has to 1) open whenever there is positive pressure coming out the valve cover port for this path 2) probably closes whenever there is vacuum at this port. In any case, this pipe has to be able to blow air towards the turbo intake whenever the port is blowing pressurized air.

In reality, I think path 2 sucking some air back into the crank case from front of the turbo is not an issue. You just want to equalize crank case pressure. If IM suction is so high that it draws air from front of the turbo, probably not a problem. Volvo turbos I worked on works this way. How much air flow all depends on pipe/hose/inlet sizes rather than check valves.

Furthermore, the air flow rate of path 2 is important. The higher the flow rate, the more blow by gas it can vent and reduce crank case pressure. On Volvo turbo cars, people have up sized path 2 to handle higher crank case pressure as engine got older and rings allowed for more blow by.

Anyhow, this is the only sense I can make of the check valve inside the rear PCV breather (path 2) and which way it opens and closes.

And of course for those who don't want to dump oily crank case gas into the intake path, a catch can be installed.

Here is a diagram that helps with understanding. All my comments are in green with green arrows"
(Ignore the Eurojet stuff...)

The original diagram can be found in the FSI which I post here (pg 13).

For a diagram of the turbo, intake manifold, exhaust, etc you can check page 16 in this same link:

Here you have a very nice explanation also about all this.

A view of the turbo:

You can see the pipe on the top right the "crankcase breather". On my same forum post you can see:
"There are two different PCV's and two different rear breather tubes and they need to be paired together properly. [See pics in the post]; pcv w/check valve goes with rear tube w/no check valve...and then the next pair(newer revision and recommended) - [AND MINE]; pcv w/no check valve (06F 129 101 P) goes with rear tube w/check valve (06F 103 215 B). It is possible the diaphragm, inside the large disc portion, of the pcv isn't sealing and routing properly under vacuum...allowing vapor to enter the turbo inlet rather than routing it to the intake manifold directly. It could be a combination of issues as well. The forementioned rocker cover come apart inside is one. How you choose to proceed is up to you. Because you have a bunch of oil coming out of the turbo outlet...first; you need a new seal (3C0 145 117 B) there on the upper turbo outlet hose. Remove the PCV again and determine if you have the older or newer pcv. Replace just the pcv if it is the newer (hopefully it was replaced correctly if replaced previously) and both pcv and rear tube if the older. That's where I would begin"

In case you have to work on the check valve of the back (rear PCV), here is a video.

Another guy advised to check inside the upstream intercooler hose (from turbo to IC) to see if the oil was inside. The IC sits between the engine radiator (on its back, towards the engine) and the AC radiator (in front of it). To get to that hose you got to remove the front passenger wheel.

"Nice to have" Youtube videos:

1. By the way, best video I've seen on basics on how an engine works
2. Not for GTI, but watch this to understands the basics of PCV. Very nice video with much more details and this other one.
3. Good guy explaining PCV for FSI
4. Great mechanic, great video, unfortunately for the TSI but you can still learn things from it.
5. How to replace it
6. This is NOT what happened to me, but you can see different effects of a bad PCV valve here, here (similar) and here.

There you go, on the smoke, the sludge that the oil replacement guy told me...

For the latest, check my post in the forum. I'll update here when it is solved.
The following is a link along my latest suspect:
https://www.mk5golfgti.co.uk/forum/index.php/topic,117203.0.html

Found this article where it says that VW considers ok to consume 1 quart every 1k miles.
I can't believe I missed so many links talking about my car brand consuming so much oil. Anyhow, here is a good one with some recommendations to follow on things to check and oil to use.

*** CHECKING THE TURBO ***

So, I have a new theory. A turbo leak. Oil refrigerating the turbo leaks into the exhaust. One can read few cases out there. Also could be the coolant (which then gives a white smoke). Actually I had just refilled both oil and coolant and both are low after my engine put out a lot of smoke the other day.

So, got a log of my boost: https://log.tunezilla.com/s/x3rWzzSt

I am not sure I am reading these properly as spec and actual don't match. Shape does, though.

I think I may have to take this into the dealer...

** UPDATE **

Dealer confirmed is the turbo ~~><~~

How to replace it

Repair at the dealer $3k. Turbo (06F145701H) from dealer alone is $1.7k. Looks like you can buy a rebuilt one for $350 or so, but also found these cheaper new alternatives: BorgWarner for $970 and STIGAN ($650 after discount)

Checked with my usual mechanic and here is his estimate:

Turbo (06F145701H): $600 for manpower + turbo cost. If I buy the Stigan (which runs now for $580) they don't guarantee the job. If they buy it for me, they'll add $200 commission but they'll guarantee the job.

Front-right axel: $320. It made a bit of noise but seems ok so far...

Fan assembly: $500 (according to the dealer, one of my two fans has stopped working). If the other goes, I am toast.Quick search, though, shows that I can do this myself

1. Forum thread
2. Nice video
3. I would try the video first, but if that doesn't work, then fans are not that expensive.

For a second I had a doubt between these two:

1. The first one clearly says is compatible with the  06F-145-701-H. Costs $588.
2. The second one is also recommended for my car by the site, but it does not list the same PN for the turbo. It does say it is a replacement for the BPY engine which is mine (found this nice article explaining it). It is $550 and comes with the kit.

I was doubting till I notice that the second uses the same turbocharger part number: 40-30176 SG. I think I'll give it a try.