[Perusal]

Originally Posted by Billfitz

The lubricating quality of diesel fuel is one reason why diesels last longer.
I changed my filter today, 4400 miles. As I expected with the initial break-in oil it was pretty dirty, as is the oil, which I'll change in the spring.

OK, I decided not to interject again earlier but give this latest statement a few additional comments....

Diesel does have better lubricity than petrol but that is not why diesels really last longer. The lubricity does help in terms of anti-wear etc.. The additive packages with which modern diesel fuels are dosed (to replace the Sulfur lost with the move to City diesel as a result of Sulfur related emissions restrictions ) certainly do help in the areas of preventing fuel pump seizure etc.

The two major determinants in determining a requirement for an oil change are insolubles content and additive depletion. Insolubles are far more of an issues in diesel fuels than petrol owing to the higher level of hydro-carbons so insoluble content is rarely much of an issue for Petrol engines....but don't kid yourself that diesel is an oil and petrol isn't. They both come from the same crude feedstock albeit at different distillation points in the cracker.

However the additives responsible for keeping the engine clean, for neutralising any combustion derived acids and for keeping any water/condensation in suspension etc do deplete over time. In fact you would expect the diesel lubricant to need changing much earlier than the petrol engine lubricant though technology advances have overcome that to a great extent.

The other reason why Diesel engines last longer is because they are compression-ignition engines as opposed to spark-ignition petrol engines and so operate at a much higher compression ratio, typically >14:1 and hence they are built to be far more robust in the first place. This is also why you see so many trucks with such phenomenal mile ages.

[kbsilver]

Originally Posted by Billfitz

The lubricating quality of diesel fuel is one reason why diesels last longer.
I changed my filter today, 4400 miles. As I expected with the initial break-in oil it was pretty dirty, as is the oil, which I'll change in the spring.

Let's not forget that with a diesel, the oil builds up with soot, another reason not to go real long between changes. This is why it turns jet black within a few hundred miles of changing it.

[Billfitz]

Originally Posted by kbsilver

Let's not forget that with a diesel, the oil builds up with soot, another reason not to go real long between changes. This is why it turns jet black within a few hundred miles of changing it.

That has no bearing on my result, as I don't have diesel.
The main advantage to wear with diesel is when moving parts are exposed to gasoline, such as rings and valve stems, they're 'washed' clean of lubricant, whereas with diesel fuel they're bathed in lubricant.

[Perusal]

Originally Posted by kbsilver

Let's not forget that with a diesel, the oil builds up with soot, another reason not to go real long between changes. This is why it turns jet black within a few hundred miles of changing it.

Those are the insolubles I am talking about, the oils ability to retain the soot in suspension is linked to its detergency - cleaning the soot from the piston rings etc and its dispersants which hold said matter finely dispersed in suspension until such time as the oil is changed.....and as a couple of us have said, over here in Europe that can be anything from 18-24 months.

Given that diesel produces so much more by way of contaminants that's why I struggle to see why cleaner burning gasoline engines can't go equally as long between oil changes....but that's back to where we started

[Perusal]

Originally Posted by Billfitz

That has no bearing on my result, as I don't have diesel.
The main advantage to wear with diesel is when moving parts are exposed to gasoline, such as rings and valve stems, they're 'washed' clean of lubricant, whereas with diesel fuel they're bathed in lubricant.

Really? Maybe in old gasoline engines with carburettors or indirect injection diesels but with today's direct injection gasoline and Diesel engines where the fuel is atomised at high pressure directly into the combustion area above the piston there's not much opportunity for raw fuel / metal contact before combustion commences.....as I said before diesel is a fuel just like gasoline albeit I do agree the 'feel' of diesel is far more oily to touch.

Wear in modern combustion engines is minimal which is why tolerances can be so much tighter today than used to be the case.

[granCLop]

Coming up on our second oil change at 16k miles, also a 2015. Dealer said we can make appt 1k miles out. Odd our indicator is at 8k and yours hasn't come up?

[Frzdrdhppy]

Originally Posted by bueller

I do not put a lot of mileage on my car, and my dealer will do a 'low mileage' oil change annually at no charge.

Even if it were not free, and probably not absolutely necessary if you are running synthetic, the piece of mind is worthwhile to me.

B.

Same here, that's what my dealer does. I remember my first BMW after coming out of years of "muscle" cars. My BMW then had lighted bars that would go out, and when the final one did it was then time for service. I couldn't stand it, especially from years of changing the break-in oil at 2-3k and then changing every 3-4k after that. I was freaking after 7500 miles and paid for an oil change myself just so I could sleep, haha The old german at Lauderdale BMW thought I was nuts and gave me great info about BMW engines and tolerances. Cool old guy!

[lens]

Originally Posted by Frzdrdhppy

Same here, that's what my dealer does. I remember my first BMW after coming out of years of "muscle" cars. My BMW then had lighted bars that would go out, and when the final one did it was then time for service. I couldn't stand it, especially from years of changing the break-in oil at 2-3k and then changing every 3-4k after that. I was freaking after 7500 miles and paid for an oil change myself just so I could sleep, haha The old german at Lauderdale BMW thought I was nuts and gave me great info about BMW engines and tolerances. Cool old guy!

I just did that on mine as well, changed it at 7500 miles and paid myself, and the next maintenance is in 8500 miles, and it's my 80,000KM service, so spark plugs (I think) oil and filter and probably microfilter.

The computer says oil change every 30,000KM but I don't trust it, if anything I'll change the filter in half that.

[Billfitz]

I got an email from BMWNA last week. My iDrive told them I was due for an oil change, and they wanted to make sure I got the message. They told my dealer too, who called me yesterday to set up an appointment. I told them I only have 4700 miles on it, but they said it's 10,000 miles or yearly, whichever comes first. I still won't bother until spring. Experience tells me that if I book an appointment in winter the chance of snow that day will be 100%.

[sushkr]

Originally Posted by Billfitz

I got an email from BMWNA last week. My iDrive told them I was due for an oil change, and they wanted to make sure I got the message. They told my dealer too, who called me yesterday to set up an appointment. I told them I only have 4700 miles on it, but they said it's 10,000 miles or yearly, whichever comes first. I still won't bother until spring. Experience tells me that if I book an appointment in winter the chance of snow that day will be 100%.

Make sure they won't void car warranty if you don't follow the recommended service schedule. The fine print on the 4-yr warranty says all recommended service should be followed.

[Billfitz]

When service is mandatory you get a warning flag in the dash display. While my iDrive currently says I can do an oil change in January it also says that it's not required for another 3900 miles. The one is based on length of ownership, the other on driver habits. I'll get it changed long before I put on another 3900 miles, which wouldn't happen until next September or thereabouts.