But the 15,000 mile/24,000 km recommendation isn't actually a recommendation, it is a starting point. Given my actual fuel consumption, the on-board computer had taken the X3 out to just over 27,000 km.

Look and see how much soot you see out the exhaust. They are much cleaner than diesels used to be. The amount of soot that comes out the exhaust (almost none) is proportional to the amount that enters the oil sump. Yes, I agree post-combustion cleaning helps, and it does, but more complete combustion results in cleaner exhaust before it ever gets to the post-treatment system.

Metalurgy has changed over the past few decades. Tolerances are generally tighter, and surface finishes better, meaning that the engine is smoother-running and has fewer corners to be knocked off (resulting in less of a requirement for an early first oil change). Tighter tolerances doesn't imply to me that the oil passages are smaller, rather that there is less wear metal to clog them.

I am not sure if engines are more or less susceptible to viscosity changes, I would be guessing. But I do know that modern oils (eg API SL, SM) are much less susceptible to changing viscosity. I would say that oils have improved many times more than the demands on them have over the past few decades.

I think that the biggest difference is that we are now running many LEV and ULEV engines. Decades ago, oils were largely degraded by byproducts of combustion in years past. Take away that built-in contamination source, and oils stay clean much longer. We are talking orders of magnitude in the scale of the reduction in contaminants.

I am absolutely sure that there are debates at the manufacturers on service intervals. My dad worked at Ford, I work with another large engine manufacturer. What would be very telling to me is if I saw a modern engine fail from following the manufacturer's service intervals. I haven't. They have safety factors built in. If you are in an extreme service application, you should definitely change oil more often. However, for the vast majority of owners, with normal duty cycles, the manufacturer's recommendation is pretty sound. Changing oil every 3000-5000 miles because we all used to do that in the '70s is, to me, like watching a Betamax on a 26" CRT, defending the picture quality, and claiming that Blu-Ray is a plot by the manufacturers to sell DVDs and LCDs which are no better than VHS tapes. Technology has moved on, on many fronts.

I am not out to change anyone's oil change habits. We will all do what we want to do. I change oil myself (as you do) because I like the experience, it is honest work, it feels good. I just don't think that new owners should be led to believe that they have to change oil more frequently because of a supposed plot by the manufacturers. There is no connection with free maintenance and extended service intervals in BMW's case (very few countries get pre-paid maintenance, while all got the extended service intervals).

I agree with others that there isn't a resolution to this eternal debate (until we see a deluge of failed engines from following the manufacturer's recommendations) but at least it is entertaining.

> Tolerances are generally tighter, and surface finishes better, meaning that the engine is smoother-running and has fewer corners to be knocked off (resulting in less of a requirement for an early first oil change).

That may be; however, when I purchased my Z4 new in 2004, I decided to get some real data, having oil analysis done on a sample take "as delivered" with 14 miles on the odo, a sample at around 2,000 miles when I changed the oil, and another sample at around 4,000 miles.

Guess what?

In the first 2,000 miles there was approximately five times the wear metals in the oil as in the second 2,000 miles.

Now, this does not prove anything as to the need for, or impact of, an early initial oil change; however, it clearly shows that in modern engines there still is some "break-in" action going on which involves a wear rate several times that of a "broken-in" engine... or at least the one BMW put into my Z4.


I might also add that BMW still requires an early first oil change for their M models. If your logic held, this would suggest the non-M engines have "Tolerances generally tighter, and surface finishes better, meaning that the engine is smoother-running and has fewer corners to be knocked off" than the M engines. Since I am sure you did not mean to imply that, then there must be something else going on that has BMW specifying an early first oil change for the M engines.

That seems reasonable. I agree that there will be more wear metals produced per mile in the inital engine life, but as you note, that doesn't make the oil bad and require an oil change. Mass spectrometers used in oil analysis are not measuring particles, they are measuring trace elements. Particles are taken out by the filter. You are really getting some insight into your engine wear rates, not your oil quality.

I was referring to the same engine produced years ago, versus one produced today. With the M engines, there is lots else going on. The manufacturing process is different with the M engines (cylinder liner surface finish, for example). The oil requirement is different than non-M models (usually 10W-60 for the M models, depending on year of manufacture and which specific piston ring is installed). Finally, if I as a manufacturer was using a 10W-60 engine oil, I would use a different oil for the initial fill. Since BMW specifies a first M oil change at something like 1200 miles, I suspect they too are using a break-in oil. To suggest that the BMW M model requirement for an initial oil change somehow supports doing one in a non-M model would require that all the above variables are somehow equalized.

So can anyone walk me through a DIY oil change on a 35d?? I have a full set of most tools but do not have oil collecting or draining tanks etc. Also, if your doing your own oil changes on a diesel is anyone finding the urea fluid that is supposed to be replenished when the car gets serviced by BMW?
Thanks!

The fluid is universal. This fall, you should be able to find it at truck stops, or any BMW dealer or Mercedes dealer.

All 2010 diesel vehicles will be required to run urea...

Craig

Didn't you read my delivery posts :D

During my delivery (yesterday) I really did get the parts dept to show me a bottle of the "exhaust fluid" and I verified, with my SA present, the info on page 247 of the X5 owner's manual including the location of the refilling receptacle. The approx 1.5 gal translucent bottle of exhaust fluid looks like a cross between a bowling pin and a kids plastic bat. I was told that it cost roughly $25.

But I think you may be getting ahead of yourself. The urea fluid is "supposed to be replenished when the car gets serviced by BMW" because your X5 35d's supply of urea should run out close to the time of the normal oil service. AFAIK If you are doing an oil/filter change ahead of schedule you do not need touch the urea unless it is low.

Funf Dreisig

I'm an avid engine professional. I've driven VW turbo-diesels for many years. In my VWs, I use Euro Elf seventh generation full synthetic and do the changes myself (even under warranty, I perform all maint/repairs myself) and I perform a 30 pt oil analysis via Caterpillar engineering after roughly 15,000 mls on each change and always completely change via extraction at 20k mls. I've logged more than 600,000 miles on 2 of these little VW diesels using synthetics. My current '05 now has 160k mls and runs better than the day it was new (compression wise).

So - my new X5 35d has 1,600 mls on it now and I don't plan on changing the oil earlier than the factory intervals. The Castrol synthetic BMW is using will easily go beyond 15k mls.

Lastly, myself and many colleagues have performed oil analysis on engines changed at 3k, 5k, 10k, and 20k mls. What we've found is early changes promote metal wear and other early engine wear (sounds counter to logic, but there really is a science behind it). I wouldn't change the oil in my X5 35d early if you paid me.

Yeah, the urea is supposed to be nasty stuff. That container is supposed to deliver the fluid into the car without any fumes escaping or spillage. It would be nice to do it yourself to know that it was done right and properly. In doing my homework before buying the 35d I found a few posts that indicated early warnings coming on with only 1 or 2 thousand miles on the car. There few if any BMW dealers when you get away from the metro areas. Before heading out for a long trip it would be good to know the system was truly full. In another year, truck stops will have this stuff. But that is a ways out.