Causes of oil consumption in new cars?

Hello everyone,

There are always occasional cases of new engines exhibiting unusually high oil consumption.
The VAG owner's manuals state that up to 1 liter / 1000 km is normal, but I think we can agree that this no longer aligns with today's standards, and that 1 liter / 1000 km on a new engine indicates some kind of defect.

Therefore, I wonder what can cause the high oil consumption of individual engines.

Could assembly errors (in my opinion, potential errors) – such as missing valve stem seals, missing oil scraper rings, incorrect KGE [cylinder head gasket] parts, etc. – be detected through other clear symptoms during operation, besides just increased oil consumption, without disassembling the engine? So, are we talking about things like piston slap, blue smoke from the exhaust during acceleration, or similar issues?
Or, conversely: would the causes of excessive oil consumption lie elsewhere if the engine shows no abnormalities during operation?

Sure, here's the translation:

"For example, elsewhere in this area:"
At least in the past, it was said that engines that were started too abruptly would become oil-burning engines.
When I imagine how the cars are moved from the production hall, to the storage area, onto the transporter, and then down to the dealer's lot, etc., before being delivered to the customer, I'm sure that the engines are not warmed up during these movements.
We would therefore likely drive those vehicles with the pristine and cold engines very carefully.
Given the "not my problem" mentality prevalent today, I unfortunately suspect that these vehicles are not being driven with much care, especially when the driver is in a bad mood or has the time and inclination for an extra lap (full-throttle starts with a cold engine until the rev limiter, etc.).

Could this be the reason why isolated cases of new engines consuming excessive amounts of oil occasionally appear, and why owners are invariably denied warranty claims with the excuse that "1 liter per 1000 km is still considered normal"?
And that VAG hasn't adjusted the 1-liter limit, among other things, in order to avoid having to replace engines under warranty in such cases?

Could a new buyer, when purchasing engines that were already known to be prone to oil consumption before delivery, have the potential for oil consumption checked, for example, by an endoscopic examination (through the glow plug or ESD bore), to detect signs of wear in the cylinder walls or similar, in order to substantiate a warranty claim for a new engine?

Or do such modifications to engines potentially lead to more easily detectable consequences, such as a noticeable loss of compression?

Or are modern engines so insensitive right from the start that they only start consuming excessive amounts of oil if, for example, they are repeatedly driven to their maximum RPM (more than 20 times) directly after cold starts, meaning that the driver is more likely to be the cause than the few miles driven before delivery?

How are the functional tests conducted for newly assembled engines? If it were to immediately go to the maximum power setting from the start, without waiting for the normal operating temperature to be reached, I could imagine that subsequent brief periods of stress on the cold engine would have little further impact... ?

Is there a rule of thumb for estimating the oil consumption of a new engine after the break-in period, such as "It definitely won't be more than half of the break-in consumption"?

Many questions, but I hope that at least some of them can be answered definitively here.

Hi Ulf,

Well, you seem to be worried about your new car!
'In my opinion, improperly installed oil scraper rings or valve stem seals are likely to quickly lead to significant oil leakage from the valve cover. Measurements like the KGE pressure can also be taken relatively quickly. Furthermore, you still have the new car warranty.' And by the time it's completely run out, you've probably figured out how much oil the car is consuming.

I can only speak from my experience as a developer of engine assembly machines for I4/I5 diesel engines (don't worry, it was Ford ). I know that the bearing surfaces for assembly are oiled. After that, the engines can only be rotated three times in so-called cold tests, for example, for measuring piston protrusion, etc., because there is no oil for lubrication. During the hot test, the machine is listened to again to see if all bearing shells are in place or if anything else is "clattering." And the cylinder bores are indexed (compression) through the glow plug holes. If too little oil is used in the cold test, I believe that "scratches" can occur. The main cause of oil consumption is likely (speculation) due to the introduction of engines from repair cycles, which then need to be revved up more often when cold compared to engines that have been running normally.
Stay cheerful.
OlBe
P.S.: @Marco, actually, the pressure measurement with the KGE is done that way in the Hottest system...

Marco wrote:

Furthermore, there's also the new product guarantee. And by the time it's run out, you've certainly figured out how much oil the car consumes.

Hi Marco,
Warranty, of course... if, for example, the consumption turns out to be 0.8 liters / 1000 km, then according to the manual, there will likely be no warranty coverage .

Or, one must ensure that the oil consumption increases even further – namely, to over 1 liter – by means of an (or several) appropriate treatment of the engine itself.

hi Ulf!

You're really worried... I can hardly imagine that at VW/Seat and the rest of the world (excluding the really high-end brands), there isn't at least one employee who takes care of the cars while they're being moved along the assembly line, warms them up properly, and is very careful. I also once saw, while filling up gas across from a car dealership, a truck driver unloading cars from his transporter. He was backing up as much as possible, putting the car in first gear while it was rolling, not using the brakes if he just gave it enough gas, and driving in with spinning wheels into the entrance. I just thought, "What kind of people are these?" It's a shame what's happening to new cars these days.
I was even more anxious when I had to pick up my car in the Netherlands, thinking about how much longer the shipping process would take. But when I finally saw the car, I have to say, no matter how it was driven before, the people in the Netherlands are very kind, and few here are as nice as a Dutch VW owner. The car was completely full of gas, incredibly clean, and the markings on all the tires were still evenly present. The KM score was 12, which I didn't find to be too high.

I don't think you'll ever be able to influence that, unless you steal the car directly from the assembly line or manage to get the Polo there. What becomes difficult.
Since, in my opinion, 1 liter can only be the result of a serious defect, you'll find it if there is one.
I'm excluding forgotten parts today; they can't afford to do that!

Even though I might be the only one with this opinion, I still believe that new engines need to be broken in. Our relatively new PD TDI engines at work also consume oil, and this has been happening for the past 27,000 kilometers in 6 months. However, no one ever thought about breaking them in properly; they were just put in and driven, and the engines weren't treated gently from the beginning. While the oil consumption has decreased, my old Golf3 TDI with almost 180,000 km needs significantly less oil.

x world one wrote:

... Our relatively new PD TDI engines, even when working, also consume oil...

... I can only confirm that PD engines are oil-guzzlers... consuming 0.5 liters of oil over 18,000 km is definitely way too much.


Okay, I can only describe it based on the various test vehicles in our fleet: First, they consume oil in a way that makes you think something is broken, and then, suddenly, they settle into an oil consumption of 0.1 liters per 1000 km.

I tend to agree more with OlBe's theory.

The break-in period doesn't seem to be the problem. My AXR was also a rental car before me, and it certainly wasn't driven gently (although there are always exceptions).

@x world online:

Quote:

Even if I may be alone in my opinion, but I still believe that new engines need to be broken in.

Huh? Which statement of the above? Is Postings seriously claiming that?

Of course, a new engine still needs to be broken in. Nothing will change quickly unless engine manufacturers run the engines through a break-in cycle on a test bench before installing them in a new vehicle.
However, this is already hampered by the costs and the amount of time required. Therefore, we will continue to leave this up to the customers.

Regards,
Alex.

Oh dear... a sensitive topic...

Okay, so my beloved 1.3S used to consume 1.5 liters of oil per 1000 km. When starting the engine, there was a cloud of smoke that would probably call out the GSG-9 (a German special forces unit) these days. High-speed driving led to tactical fogging. The main reason for the excessive smoke on startup was the valve stem seals, which were replaced after a valve spring broke. However, after the replacement, the oil consumption only decreased moderately, which probably meant the piston rings were also worn.
The engine then failed due to the cylinder with the broken spring, probably because I had this issue at 190,000 km and had to tow the car 25 km on three cylinders. This likely caused some lubrication problems. It finally died at 220,000 km (which die-hard 1.3S owners still find hard to believe, but mine was before the famous production run...).

The treatment immediately after birth is a tricky thing. It will certainly play a significant role in the oil consumption. Frankly, I can't imagine that these engines are generally being thrown out. If someone in a management position finds out about it, there will likely be complaints.
If they are naturally being loaded onto the truck... at least the VW driver on site doesn't dare to do it; he probably received a complaint once. Write down the date, time, and number, and/or ask for the manager at the counter... that often works wonders with the shipping company.

I still believe that the initial run-in phase is extremely important. I am aware of the tolerances that apply in manufacturing, and while high-speed machining is certainly not bad, with all due respect, it becomes too expensive in the micrometer range; everything eventually becomes too expensive. The run-in phase is still necessary!

They probably didn't handle my ALH gently either (due to the automatic transmission), but in my case, it was initially 'treated according to regulations' (and you know how incredibly annoying that is). It needed its first oil change after 25,000 km.
The colleague's company car, however, was not spared. It was driven with a three-digit mileage until the very end. The maintenance interval for the oil change was around 10,000 km, but it wasn't quite full when it was handed over (max. 3/4). Let's see how things develop from here...

Where do outliers come from, then?

The machine tool has a tool management system. This means that, ideally, the tool life is determined by re-measuring (even during the machining process), but in the worst case, it's based on time. Consequently, the tolerances change during the machining of a series. They certainly don't exceed the specifications, but if a few factors happen to coincide negatively -> it's a problem.

or the vacation substitute chokes on a piston ring and doesn't tell anyone because he's afraid of getting yelled at (and I HATE that, nobody's ever been yelled at yet, you damn cowards, grumble...). And just like that, you have another candidate.

or there might still be some debris inside that's causing scratching, or the loader manufacturer might have widened their tolerances.

Ultimately, it will be a summation of small things, and I'm most inclined to believe the story about the tools. ING's sometimes do strange things at VAG .

btw: a good reference source states that a consumption of 0.1 - 0.25 liters / 1000 km is considered normal, while consumption rates of 1 liter / 1000 km or more would indicate a defect. Doesn't VAG also rely on independent experts?

CU Gremlin.

Hello everyone...


In my opinion, modern engines hardly need any break-in period anymore.
The tolerances are now so precise and good; only the piston rings need to be slightly worn in.
This likely happened after only 100-200 kilometers.
But revving a new engine all the way up to the redline when it's cold is definitely .

There was once a report in a car magazine (Auto-Blöd). They repeatedly found evidence of piston seizure marks in Japanese cars, but it apparently didn't affect the engine's lifespan. These seizure marks originate from the issue mentioned above. Handling procedures during the loading and unloading of transport ships.

I personally once 'ran in' a brand new Ford Zetec on the racetrack, meaning I only revved it up to 5,500 RPM for the first 40-50 kilometers, and then I gradually increased it to 8,500 RPM.
And it wasn't warmed up for long either; there wasn't time for more than one lap.

After approximately 800 km, I had the 'opportunity' to see the inside of the engine (it had exploded while running at 9,000 RPM).
Not a single puff from the remaining 3 cylinders.

@leolotus:

Quote:

In my opinion, today's engines hardly need any break-in period anymore. The tolerances are now so precise and good; only the piston rings need to be slightly worn in. This has likely already happened after 100-200 km.

I'm sorry, but I completely disagree. How do you explain the fact that I could still notice break-in effects in my TDI even after 10,000 km?

Furthermore, no matter how good the surface finish, it cannot replace the final running-in process of sliding surfaces; at best, it can shorten it.

Regards,
Alex.

@leolotus:

In my opinion, today's engines hardly need any break-in period anymore.
The tolerances are now so precise and good; only the piston rings need to be slightly worn in.
This has likely already happened after 100-200 km.

I'm sorry, but I completely disagree. How do you explain the fact that I could still notice break-in effects in my TDI even after 10,000 km?

Furthermore, no matter how good the surface finish, it cannot replace the final running-in process of sliding surfaces; at best, it can shorten it.

Regards,
Alex


I'm not saying that new engines should be immediately pushed to their limits.
Of course, the surfaces are still bedding in today, and the oil consumption will decrease until 10,000 km, and the performance will increase by then.
It's probably due, among other things, to the extremely hard piston rings.
I can definitely imagine that this also applies to the sealing surfaces in the PD elements and the ESP, meaning that perhaps the full pressure isn't present right from the start.

I just wanted to say that an engine that is somewhat warm, and perhaps has been driven gently for the first 50-100 kilometers, can probably handle a bit more stress.

What's even worse for the pistons is high TORQUE!!!
This causes the pistons to tilt to the side, and the piston skirt rubs violently against the cylinder wall!

And for (new) camshafts, very low RPMs are actually extremely detrimental!
High-performance camshafts should not be run at speeds lower than approximately 2500 RPM for the first few minutes.

However, what is always completely overlooked when it comes to 'breaking in' a new vehicle is the transmission.
Here too, high torque is harmful, not high speed.

My conclusion: Properly warm up the engine before starting, and for the first 100-200 kilometers (in one go, without any further cold starts), break it in by varying the engine speed and not using too much torque.
After that, assuming a sensible driving style, there's very little you can do wrong.

PS

According to the workshop manual for my 125cc Honda Elsinore (full-crosser, manufactured in 1976), for a completely overhauled engine, the break-in procedure was simply 'run it for 5 minutes at a slightly elevated idle speed'!!!

I can only speak from my experience as a developer of engine assembly machines for I4/I5 diesel engines (don't worry, it was Ford ). I know that the surfaces used for assembly are oiled. After that, the engines can only be rotated three times during so-called cold tests, for example, for measuring piston protrusion, etc., because there is no oil for lubrication. During the hot test, the machine is listened to again to see if all bearing shells are in place or if anything else is 'clattering.' And the cylinder bores are indexed (compression) through the glow plug holes. If too little oil is used during the cold test, I believe that 'scratches' can occur. The main cause of oil consumption is likely (speculation) due to the introduction of engines from repair cycles, which then need to be revved up more often when cold compared to engines that have been running normally.
Stay cheerful.
OlBe
P.S.: @Marco, the thing about the KGE pressure measurement is actually done that way in the Hottest...

I can only come to terms with this explanation.
because manufacturing machines, quality control, and materials have all improved significantly in recent years, leading to a higher degree of certainty.
Of course, this also leads to some savings here and there.
Based on my experience with mopeds, I can say that...
Engines that have been 'broken in' with a focus on performance often deliver more power in later operation.
without significantly affecting its lifespan.

Okay, here's a different question:
Why is it necessary to warm up an engine before driving?
Please provide solid justifications.
The operating temperature of an engine, specifically a gasoline engine, is more or less arbitrarily set and is essentially only limited to below 100°C.
'Because the water used for cooling starts to boil at over 100°C under normal pressure, the operating temperature is arbitrarily set, aside from the temperature difference between the combustion chamber and the cooling water.'
greetings

Hello everyone,

First of all, thank you for your previous contributions. Although the results may be partially contradictory, perhaps we can still reach a well-supported overall conclusion -> please continue posting.

Bertil wrote:

So, I can only describe it based on the various test vehicles in our fleet: first, they consume oil in a way that makes you think something is broken, and then, suddenly, they settle down with an oil consumption of 0.1L/1000km.

An interesting story.

Here are a few questions to help solidify the information:

-> Approximately how many cars does this refer to in total?

-> What is the consumption rate initially (approximately), and what is the range of variation?

-> approximately Will the final consumption reach approximately 0.1 liters?

-> Do you have any clear correlations between driving style and the individual development of oil consumption (which would likely only be possible if the vehicles are somehow assigned to specific individuals and the individual drivers have correspondingly different driving styles)?

After approximately 800 km, I had the 'opportunity' to see the inside of the engine (it had exploded while running at 9,000 RPM).
Not a single puff from the remaining 3 cylinders.

Well, the fourth one probably would have lasted longer if it hadn't suffered damage from being driven without being properly warmed up first...
Things like layer cross-sections or the installation of seals play a role.
and: manufacturing accuracy has nothing to do with surface roughness.


Okay, here's a different question:
Why is it necessary to warm up an engine before driving?
Please provide solid justifications.
The operating temperature of an engine, specifically a gasoline engine, is more or less arbitrarily set and is actually only limited to below 100°C .

'Actually, nothing is that arbitrarily defined. Generally, engine manufacturers want the highest possible operating temperature because that's when efficiency is best. In mass production, the cost factor comes into play, which is why there's a compromise at around 90°C (not least because water is used as a coolant).'

A motor running in operation will inevitably get warm. This is unavoidable and, in fact, can be a good thing (see above). Now, I need to ensure that all components function optimally together at this operating temperature. This has consequences!
For example, the pistons are typically made of lightweight metal, while the engine block is usually made of gray cast iron. This already presents a problem: the different thermal expansion rates. Furthermore, the piston clearance must be correct when the engine is warm. This means that the pistons have significantly more clearance when the engine is cold. The same applies to the cylinder head: valves made of steel, head made of lightweight metal. Similarly, the bearings consist of lightweight metal bearing shells running in a gray cast iron bearing housing.
All of this leads to the engine components being somewhat uneven at room temperature. The pistons are smaller at the top than at the bottom when cold, and the cylinders are oval, etc.

Then, fuel condenses on the cold cylinder walls (otherwise, a choke wouldn't be necessary) and can potentially wash away the lubricating film. The oil needs a minimum temperature to fully fulfill its lubricating function, etc.

That's why it's necessary to let the engine warm up, not least because these things are manufactured with increasing precision.

CU Gremlin.

Hi Ulf,

ulf wrote:

Bertil wrote: So, I can only describe it based on the various test vehicles in our fleet: first, they consume oil in a way that makes you think something is broken, and then, suddenly, they settle down with an oil consumption of 0.1L/1000km. An interesting story. Here are a few questions to help solidify the information: -> Approximately how many cars does this refer to in total?

Since the cars are constantly being changed, I can't give you an exact number (but there are usually around 10-20 cars going through at any given time).

Quote:

-> What is the consumption rate initially (approximately), and what is the range of variation?

Initially, about 1-1.5 liters. However, there are also vehicles that have consumption figures as low as 0.1L to 0.3L.

Quote:

-> At what approximate mileage is the final fuel consumption of approximately 0.1 liters reached?

That also varies, but around 15,000 km, all of them have almost the same oil consumption.

Quote:

-> Do you have any clear correlations between driving style and the individual development of oil consumption (which would likely only be possible if the vehicles are somehow assigned to specific individuals and the individual drivers have correspondingly different driving styles)?

That would be an interesting aspect, but unfortunately, our focus is less on the engines, so there are no studies or even defined driving cycles related to them. Also, the vehicles are not always driven by the same people. What I can say, however, is that the engines are by no means spared (regarding things like warming up or running gently... ).