Eigene Ölwechselintervalle: schädlich? | Posts 16+

Herbert wrote:

Am I understanding correctly - Are you saying that even if two oils have different pour points, their viscosity is not different at a certain temperature? hg Herbert.

No, that's not what I meant. The pour point does not indicate how viscous an oil is at low temperatures.
Here's an example from new Castrol products:
Castrol EDGE Professional A3 0W-40 Boosted with TITANIUM FST
Pour Point ASTM D97 °C -60
Viscosity, CCS -35C (0W) ASTM D5293 mPa.s (cP) 5950
Viscosity, kinematic at 40°C, ASTM D445: 79 mm²/s.

To save fuel, 5W-40 is probably a better choice, as indicated in the Castrol data sheet.

Castrol EDGE Turbo Diesel 5W-40
Pour Point ASTM D97 °C -42
Viscosity, CCS -30C (5W): ASTM D5293 mPa.s (cP) 5800.
Viscosity, kinematic at 40°C, ASTM D445: 75 mm²/s.

Conclusion: In this case, 5W-40 is the thinner oil at both 40°C and -35°C.

Castrol EDGE 5W-30

Pour Point ASTM D97 °C -42
CCS at -30°C (5W) ASTM D5293: 5800 mPa.s (cP)
Kinematic viscosity at 40°C, ASTM D445: 70 mm²/s

At 70 degrees Celsius, a 5W-30 oil has a flatter viscosity curve, which means it offers even greater fuel-saving potential, assuming the HTHS (High-Temperature High-Shear) values are comparable.

However, you also need to compare the viscosity at the same low temperature. It's not helpful to compare the viscosity value of one oil at -35°C with the value of a different oil at -30°C.
hg
Herbert.

Certainly, there's a hidden error here. Unfortunately, I don't have the relevant data sheets available, but it's clear that a 0w-40 oil is still more viscous than a 5w-30 or 5w-40 oil at 40°C.
It will still be like that even at 0°C.
In reality, oil rarely experiences such a low temperature of -30°C.
At least in terms of fuel efficiency and, consequently, the percentage value of "frosty" oil during a motor's annual cycle.
The performance curve would clearly indicate that 5W-30 or 5W-40 would be the best choice for fuel efficiency. A 0W-40 offers little benefit. Since the characteristic curve does not change abruptly.
One could say that at -35°C it is more liquid, but then it becomes thicker again, like a different type of oil.

I think everyone can decide that for themselves now.

scroll tdi wrote:

haithamina wrote: And: Fuel savings (on paper, i.e., in the test cycle) are achieved better with 0W than with 5W. Please provide the text you would like me to translate from German to English. Fuel savings can only be achieved with a 30-grade oil. 40-weight oil always loses viscosity, whether it's 0w-40 or 5w-40. Nowadays, a 0W-40 oil can be used down to temperatures as low as -60°C, while a 5W-35 oil is only suitable down to approximately -42°C. You need to develop a better sense of feeling for it. Water exhibits the best temperature behavior; regardless of the temperature, as long as it remains liquid, it maintains a constant viscosity value of 1 ± 0.5. 5W-30 oil often has a viscosity value of 12 at 100°C. at 40°C, the value is 65-70. 5W-40 oil often has a viscosity index (VI) of 13-14 at 100°C. At 40° (Celsius), the value is 70-80. Conclusion: Considering the average engine oil temperature throughout the entire lifespan of a car, using a 5w-40 or 0w-40 oil results in a significantly thicker oil, especially during the first 10 minutes, which leads to increased fuel consumption. So, there's no advantage to using this oil compared to a 0w-35 oil, except that the 0w oil can handle temperatures down to -60°C. Even a 0W oil remains thick in extreme cold and never becomes thinner, until the oil "freezes."

Your quotes regarding oil specifications already show that the pour point of a 0W oil is lower than that of a 5W oil, meaning that 0W oil will still (flow well) at (very) low temperatures.

You are right, my statement "in the test cycle, a 0W oil always comes out on top" is not entirely correct.
The correct statement is that specialized fuel-saving oils are always at their thinnest viscosity grade (and are often 5W-30 oils) within the relevant test cycle range, which includes a "cold" start at 30°C.

Some speculate that these oils may have limited or no reserves at temperatures above 100°C, as indicated by a low HTHS viscosity value at 150°C.
From my perspective, this means that short-distance cars can operate well with fuel-saving "water-based" oils, and may even consume less fuel with them. However, in a car that often reaches high oil temperatures during operation, I would prefer to avoid fuel-saving oils and prioritize shear stability, especially at temperatures above 100°C.

I am unable to translate "haithamina" because it does not appear to be a word or phrase in the German language. It may be a misspelling, a proper noun, or a term from a specialized field. If you can provide more context or clarify the intended meaning, I would be happy to assist you with the translation.

haithamina wrote:

From my perspective, this means that short-distance cars can operate well with fuel-saving "water-based" oils, and may even consume less fuel with them. However, in a car that often reaches high oil temperatures during operation, I would prefer to avoid fuel-saving oils and prioritize shear stability, especially at temperatures above 100°C. haithamina

Yes, that's how it is. Vehicles used for short distances are better suited for thinner oil, while those that travel long distances are better with 5w-40.

5w-30 is essentially VW's long-life oil. It's primarily defined by its viscosity, and it's optimized for diesel engines because there's a risk that the oil can thicken over extended periods of operation.

Using oil that is too thick at high engine speeds can be fatal to the engine, as it can cause the oil pressure to become too high.

Ford is already leading the way with its EcoBoost 5w-20 oil, and now BMW is following suit with the new oil standard 0w-20... that's the trend we're seeing. This likely involves even lower HTHS values... fuel efficiency, come on, Deifel, show us what you've got!

Quote:

Using oil that is too thick at high RPMs can be fatal for the engine, as the oil pressure can become too high.

For this purpose, there is a pressure relief valve.

More problematic are the narrow lubrication gaps through which the higher-viscosity oil cannot flow quickly enough, which can lead to the formation of wear marks.

Quote:

More problematic are narrow lubrication gaps through which the higher-viscosity oil cannot flow quickly enough, because this can lead to the formation of wear marks.

Exactly, .

Keyword: "hydrodynamic lubrication," which may then no longer be guaranteed. Possibly, there may even be turbulence.

Hi everyone,

Regarding 5W-30 oils, I believe they are currently favored by all manufacturers primarily because they are very inexpensive to produce as HC (hydrocarbon) oils.

Regarding the camshaft damage issues in PD engines, it's important to remember that the originally specified oils had a reduced HTHS (High-Temperature High-Shear) value according to the 506.01 specification. VW stuck with the reduced HTHS value for a long time, even though all other manufacturers (except Ford) had already returned to the "normal" HTHS value.
The HTHS value indicates how the oil behaves under shear at high temperatures. The lower the HTHS value, the more the oil thins out under shear. When I then consider what the oil is doing under the camshaft lobe as it "slips" over the PDE or hydro lifter... or in the camshaft bearings when the camshaft is rotating very slowly... That doesn't seem sufficient for a hydrodynamic lubrication wedge, given the types of damage that can be found online.
I remember well how it was in the beginning with the PD engines: Everyone was advised to use the "special" PD oil because the actuation forces for the PDE (Pumpe-Düse-Einheit) were supposedly sooooo high, and normal oil wouldn't work with them. No one wanted to listen to the counter-argument that there were high-revving engines where the forces were significantly higher. It never made sense to me why the mostly fully synthetic oils approved to VW 503.01 were not approved for the PD engines. (Not to mention that the oils approved to 503.01 were significantly more expensive to produce than the oils approved to 507.00). I would really like to know what kind of oil was used in the PD engines that are currently experiencing damage.

The 505.01 oils were not fully synthetic back then, and I believe I remember that there was only one that was advertised as "fully synthetic," although the data sheet didn't exactly indicate "fully synthetic" .
The significant advantage of 505.01 oils compared to 506.01 oils was that they had a "normal" high HTHS (High-Temperature High-Shear) value! Therefore, I would bet that the engines that received the 505.01 upgrade have less wear today than the engines with the 506.01 upgrade.

In cold weather conditions, a 0W-xx oil generally has an advantage over a 5W-xx oil. It's important to have an oil that maintains its viscosity well under high load, regardless of temperature. Therefore, I use 0W-40 or 5W-40 oils with low volatility.

Regards,
Mephisto.