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My car is a VW Golf 5 1.9 TDI (77 kw), year 2005.

Problem: Turbo hose broke

Yesterday while driving on the highway with a speed of around 130-140 km/h I noticed a sound from the engine which was clearly indicating that something was detached or broke and I immediately pulled over to see what is happening.

Note that I’m a noob in mechanics and I called for an advice from some friends which are more experienced and the first thing they wanted me to test is will the car drive. I started it and it was driving but the thing that I immediately realized was that it does not have the same power as before and there was this loud noise coming somewhere from the engine.

I turned it off and I called my friends to get a mechanic and to come see the car right on spot, I did not want to drive it. After the mechanic took a look he established that the hose that is connected to the turbo was broke and the noise was coming from the turbine in the turbo.
He decided that it is okay to drive the car from there to home (which is around 55 km) and on the way home as expected the car would not have the normal power. I asked him how fast should I drive and he said that there is no problem with how fast we are going and because it was on the highway I was going with a speed of around 100 km/h (120 if it was downhill) it would not go faster.

Oil draining out

During the journey towards home the car was outputting visible gray/black smoke a lot which up until that point was definitely not the case.

After a few hours I decided to check the oil (obviously it had time to settle) and it was below the minimum.

The oil indicator did not go on that it is below the minimum and even today it is still not indicating that it is below the minimum. Before driving it towards home the mechanic checked the level and it was okay (the car was not working for 1 hour before he did that, it probably had time to settle).

Note that I didn’t had any issues with my car consuming oil. The last oil change that I did was 1500 - 1700 km before this happened and I was constantly monitoring it and it stayed at the original level all the time.

Oil level after oil change

Current oil level

Questions

1. Should I add oil so that it has enough and drive it to the workshop of the mechanic? It is around 15 km from my location.


2. I guess it is not safe to drive anymore with the current level of the oil, right?


3. Is it better to just add oil or completely replace it under the current circumstances?

Don’t drive it, until you have topped up the oil. Then you can get repair it or take it to a mechanic to fit a new pipe.

Once those repairs are complete check what is causing the high oil consupmtion - it may just be due to the broken air pipe...

Not sure how much damage you have done - it may already be terminal - if not, then you have reduced the life of the engine...

I don't know enough about turbos to speculate on why this might make the engine burn oil (which yours did). The decision to drive it back home was likely fine. At worst, you've taken a bit off the engine's life, from running it with low oil. It would've been better if you could have kept the engine oil above the minimum (adding oil during the drive), and you definitely need to keep it above that starting now, but I wouldn't expect the fix to be too hard overall.

Take the car to a mechanic (after filling your oil, and maybe checking the oil along the drive to make sure it stays high enough), and have them fix the problem with your turbo. Afterword, keep an eye on your oil level. Hopefully you won't be burning oil anymore, and the oil level will stay good. If not, you'll have to separately diagnose the oil leak problem.

In bold, I'm answering the questions at face value, specific answers for your scenario are below each bold answer.

1: I would be a bit concerned about driving this car until diagnosed by a mechanic.

From the sounds of it, the high pressure oil feed for the turbo came off. Which meant you were running the turbo with no oil running through it, depending on the type of turbo it might have survived, but since you heard bad noises there's a good chance its damaged.

Continuing to drive could cause worse damage to the turbo or if the turbo breaks, and metal gets into your engine then engine damage also follows.

If it was not the high pressure oil feed (generally on top of turbo), and instead was the lower pressure oil drain (generally on bottom of turbo), your probably fine apart from having lost some oil , however based on the description of the sounds you heard it was probably the high pressure line.

2: The oil is still visible on the dipstick so that is great, your probably safe to drive a short distance (as long as there are no leaks that would bring it lower).

The real issue with low oil is, as it lowers you lose oil pressure which is what actually keeps the metal bits in the engine from touching.

Oil alone isn't enough, it must be pressurised oil.
Imagine squeezing a garden hose with the water on vs water off, when hose is pressurised you cant press it together easily, this is what stops metal from touching inside the engine.

Since you still have oil on your dipstick, that means the oil pump would still have enough oil to pickup so likely it still had good pressure.

If this was the only issue, I would not be too worried about driving it 15kms to a service station like that. Ideally top it up before you go, but it shouldn't cause any substantial damage (honestly shouldn't cause any).

However in this case the leak was caused by a turbo oil line coming off, so I would not drive even though it was reattached. Damage to the turbo could get worse or cause damage to the engine if the turbo fails.

3: So long as your within the service interval of your oil, there is no need to replace it.

Simply topping it up is fine (make sure that it is the same or better oil to what is currently in it).
Generally it is ok to mix different types of oils, however you should try to add the same or better oil.

Note: If the hose was correctly attached back by the mechanic, the oil burning off on the drive back would have likely just been oil that had sprayed onto various engine bits that get hot and was burning off.

Sources: I have built turbocharged engines entirely from scratch and have a very good understanding of how the systems work.