Oil Consumption: Causes and Solutions

Hello,

How much oil consumption is now acceptable for an engine?
My VW dealer is currently having VW check whether an oil consumption of approximately 1 liter over a distance of about 700 km is normal.

V6 2.5 TDI 4M

What experiences do you have?

--gustaf

Hi,

I only have a 4-cylinder engine, but I think I remember reading in the car's manual that 1 liter of oil per 1000 km is considered normal.
VAG even states that the wear limit is 1.5 liters per 1000 km.
I only need to top up a maximum of 0.5 liters every 15,000 km.

Hi,

If a TDI engine consumes one liter of oil per 1000 kilometers, there is definitely a problem, even if the owner's manual states it is still within acceptable limits! If there are no visible leaks, the problem is usually related to the valve stem seals (especially with high mileage) and the seals in the turbocharger. With aggressive driving, it could also be wear on the piston rings/piston bore. However, the cylinder head gasket is no longer a problem since the switch to metal gaskets, unless the engine has been overheated, which could warp the cylinder head!

Best regards, Christian.

Yes, that's something all manufacturers are still happy to do.

The oil consumption can be as high as one liter per 1000 kilometers!

In times when manufacturing tolerances are so tight, an oil consumption of 0.2 liters is already too much.

I'm curious to see when the manufacturers will rephrase that sentence!

Regards,

Manuel.

gustaf wrote:

What experiences do you have?

... I consider 0.1 liters per 1000 km to be normal, and 0.5 liters per 1000 km to be excessive (although various manufacturers consider it acceptable - not just VAG).

Anything that is significantly below 0.05 liters per 1000 km would make me concerned (due to potential oil dilution).

But be careful! Oil consumption is often heavily influenced by driving style. For example, my Jetta consumes about 0.5 liters of oil during a rally (300 km), but on leisurely Sunday drives, it uses "only" 0.4 liters per 1000 km. If you calculate the extreme consumption under extreme conditions, that's also 1.5 liters per 1000 km. Nevertheless, I wouldn't consider the engine to be defective.

@dieselgustav

I once had a Toyota Camry gasoline car (*embarrassing*) as a company car. It also consumed at least 1 liter of oil per 1000 km. According to Toyota, this was normal. However, the workshop didn't think so. They investigated the car thoroughly, but couldn't find anything. Then, a mechanic had the idea of trying 5Wxx oil instead of 0Wxx, and after 10,000 km, the oil consumption dropped to less than half a liter. No one could explain this, not even Toyota Germany, who were confronted with the problem.

Hi,

Then a mechanic came up with the idea of filling with 5Wxx instead of 0Wxx, and then, after 10,000 km, they used no more than half a liter. No one had an explanation for this, not even Toyota Germany, who were confronted with the problem.

Well, the explanation is actually quite simple.
5W has a higher viscosity than 0W.
Therefore, 5W oil doesn't leak easily and has a harder time circulating through worn-out engines.

I usually use 10W bulbs, or even 15W.
As a result, my engines have almost no oil consumption.
And they hold firm, despite the sticky mess.

@markus

Okay, I understand about the thin consistency. But the engine was new and had somewhere between 10,000 and 20,000 km on it during the experiments. There shouldn't be excessive leakage, and the wear and tear should have been within reasonable limits!

Markus H. wrote:

I usually use 10W, or even 15W. As a result, my engines have almost no oil consumption. And they hold firm, despite the sticky sludge.

Hi,

"I completely agree! Audi 80 TDI with 270,000 km, every oil change with Liqui Moly Turbo HD (15W40) for 17 euros, and it runs like the first day! You don't need those overpriced oils!"

I once read somewhere on the internet that a viscosity change is equivalent to 30,000 km of wear (written by some professor of mechanical engineering)....I wonder if that's true .

Best regards, Christian.

Hi, I can't really explain this change in viscosity; it was never discussed during my studies either.
Ultimately, the engine undergoes a viscosity change with every cold start. Cold 0w40 oil is still much thicker than warm 20w50 oil. Therefore, increased fuel consumption with 0wxx compared to 5wxx is unlikely. However, it's possible that 1. the oil company cheated, meaning the oil was too thin when warm, or 2. the viscosity ranges for automotive oils are extremely broad and inaccurate compared to the requirements for, for example, the bearing oil used in large power plant turbines. The same designation does not necessarily mean the same viscosity.

'So, my first Kadett 1.3S used 1.5 liters of oil per 1000 km. It had completely broken valve stem seals. After replacing them, it was much better.'

The 'alt-opa-kiste(tm)' (2.0i) model, after approximately 190,000 very demanding kilometers, consumed about 1.5 liters of oil every 15,000 kilometers.

The TDI still shows 3/4 on the dipstick after 17,000 km, despite using long-life oil .

In my opinion, 1 liter per 1000 km is NOT normal.

CU Gremlin.

Hello,

I also have a question about that.
Is it correct that changing the winter viscosity, for example from 5W to 0W...?
More critical than a change in summer viscosity, for example, from 40 to 50.

Background:
I would like to switch from Liqui Moly 5W-40 to Mobil 1 5W-50 because...
'I work in Luxembourg, and here, Mobil 1 5W-50 costs only 6.25 euros.'
Liter costs.

Achim wrote:

Is it correct that a change in the winter viscosity, e.g., from 5W to 0W, ... More critical than a change in summer viscosity, for example, from 40 to 50.

I don't understand what you mean by "critical." I think the 30,000 km interval for oil changes mentioned in one of the previous posts is complete nonsense.
Basically, I put whatever is currently available in the workshop into my engines, as long as it meets or exceeds the required specifications.
My tractor, manufactured in 1959, has only had its piston rings, valves, crankshaft, and connecting rod bearings replaced once during its lifetime.
Following the above 30,000 km reading, it is likely that the mileage is now well over several million km .
And my TDI with 130,000 km (oil changes every 7,500-10,000 km, not the usual 15,000 km interval) already has 300,000 km...

Achim wrote:

Background: I would like to switch from Liqui Moly 5W-40 to Mobil 1 5W-50 because... Working in Luxembourg allows me to buy Mobil 1 5W-50 for only 6.25 euros. Liter costs.

It's worth repeating: the viscosity grades are relatively unimportant in our region. What's important is the quality and intended use of the oil, meaning whether it meets the correct standard (e.g., 50501, which is specified in the car's owner's manual) or not.
If it fits, put it in.
See also http://www.dieselschrauber.de/tipstricks.html.

Best regards, Rainer.

Hello,

@Rainer K.

I meant 'critical' in the sense that switching to 0W oil is probably...
improving oil consumption compared to a change from 40 to 50.
from 50 to 40.

Achim wrote:

Hello, @Rainer K. I meant "critical" in the sense that switching to 0W oil is probably... improving oil consumption compared to a change from 40 to 50. from 50 to 40.

Okay, well I'd say just try it out... It probably depends on the specific engine/charger in each case.

It is particularly important with mineral multi-grade oils. In these oils, the oil is artificially thickened at high temperatures using viscosity improvers (long molecular chains). However, these molecules can also break down, in which case the base oil becomes crucial again.
Synthetic oil naturally has a favorable viscosity profile and should therefore be less prone to issues.