2016 BMW X5, N57 tri-turbo, 150k km, Fuchs GT1 5W30 12k km OCI

[more_fasterer]

Hi everyone, this is my first UOA so any helpful advice is appreciated.

The car in question is an X5 M50d with the N57D30S1 tri-turbo engine that has been ingesting diesel since the last oil change. That's getting fixed as soon as the timing tools arrive. It's the presence of diesel in the oil that prompted me to get a UOA done as I was concerned about elevated bearing wear due to the diluted oil (which was already quite thin to begin with...), but the copper & aluminium levels look OK. The iron levels are concerning me though.

Oil is Fuchs Titan GT1 Flex23 LL04. Oil change interval history is below, see if you can spot where someone who cares about maintenance (i.e. me) bought the car:
24,046
34,108
49,015(!!)
10,833
9,428
11,442
11,564

In the latest oil change, I've switched to to Penrite Enviro+5W40 LL04.


Cheers

 

[fantastic]

Yes, That fuel is way too high & Iron levels are real high as well. Remedy the fuel issue & wear should come back down. Does this car have a horsepower tune on it?

 

[BMWTurboDzl]

From what I've heard from an engine builder in Germany this motor is shall I say tuned to the very edge of reliability. Keep it stock and you won't crack a piston.

 

[more_fasterer]

It's completely stock.

 

[fantastic]

It's completely stock.

okay but are you "racing" it around? It appears that in your Handle ID "more_faster" & avatar you're a speed "enthusiast"?

 

[more_fasterer]

Haha, I have a rally car for racing and a GT-R for fast road driving. But I also have a strong sense of mechanical sympathy for all my vehicles.

The X5 doesn't get driven hard, it's the wrong type of car for that sort of thing. The most stress it's put under will be when towing a combined weight of 1,700kg of rally car and car trailer. It gets plenty of long drives so has ample opportunity to keep the DPF clean. I'm in a temperate climate (New Zealand) so it doesn't get subjected to extreme heat or cold either.

 

[twX]

Dilution can increase continually over an OCI with diesels, since it isn't volatile enough to completely evaporate, so a shorter OCI should help. Check for leaky injectors, and make sure your thermostat is working properly and the engine is getting up to temperature.

Phosphorus is only 419 ppm and zinc is low as well. Phosphorus should be 700-900 ppm with a C3 oil, and it wouldn't normally disappear from the oil even if the ZDDP breaks down. It could be ending up in sludge or varnish, or maybe this batch of oil was improperly formulated. The amount of phosphous from functional ZDDP would be even lower than the 419 ppm would suggest, and that might be increasing wear. Calcium and magnesium seem a bit low as well. A shorter OCI should help with the additive depletion.

Iron is very high, but PQI is very low. PQI is a measure of larger iron particles, whereas the iron ppm is a measure of only small particles. The high ratio of iron to PQI means that the iron is probably from corrosive wear, not abnormal component wear.

The corrosive wear could be due to the additive depletion that is evident from the UOA. I expect that if you tested TBN, it would be very low. The fuel dilution could have something to do with it, and there's a bit of water in the oil as well. Soot also seems very high. Poor ring seal might be allowing fuel, water, and combustion byproducts into the oil. I would do a compression test. Those 25-50k OCIs wouldn't have done the rings any favours.

Even if you don't address the problem, the engine might do alright with much shorter OCIs.

Edit: The high soot could be from running too rich due to injector problems.

 

[fantastic]

Haha, I have a rally car for racing and a GT-R for fast road driving. But I also have a strong sense of mechanical sympathy for all my vehicles.

The X5 doesn't get driven hard, it's the wrong type of car for that sort of thing. The most stress it's put under will be when towing a combined weight of 1,700kg of rally car and car trailer. It gets plenty of long drives so has ample opportunity to keep the DPF clean. I'm in a temperate climate (New Zealand) so it doesn't get subjected to extreme heat or cold either.

How often do you tow 1700 (3750 pounds)? Still need to get the fuel figured out.

Dilution can increase continually over an OCI with diesels, since it isn't volatile enough to completely evaporate, so a shorter OCI should help. Check for leaky injectors, and make sure your thermostat is working properly and the engine is getting up to temperature.

My limited experience shows it increases fuel but not at a high rate like you'd expect. 6500 mile run had 2.3% while 9500 only increased to 2.8% on my 6.0L as an example. Also, diesel fuel should be plenty volatile with enough compression but maybe that's a problem here. OP might want to rule out low compression as a starting point.

 

[more_fasterer]

Even if you don't address the problem, the engine might do alright with much shorter OCIs.

Thanks for your response, very informative. What sort of magnitude are you talking about for shorter OCIs? e.g. the 10-12,000km I'm doing now, or something closer to half that?

The thermostat appears to be working properly as the oil* temperature gauge on the dash warms up quickly and is rock solid once warm.

I'll do a compression test when the injectors are out for testing. As for the injectors themselves, an idle fuel quantity test showed minimal variation between cylinders - the biggest variation is 0.2mg/cycle, where the max acceptable variation is 3.0. See attached.

After sharing this situation with a mate who's a diesel fuel system expert, the leading hypothesis is the fuel is entering the crankcase through the seal on the fuel pump's drive spindle. I'll let you know what I find when the injectors & fuel pump are tested.

How often do you tow 1700 (3750 pounds)? Still need to get the fuel figured out.

Not as often as I would like! Once every 3-4 months, typical distance each time will be 150-200km.


*I'm not actually convinced this is an oil temperature gauge, as it warms up at the same rate as the coolant temperature in pretty much every petrol & diesel car I've ever owned - and certainly far quicker than the oil temperatures in the petrol-powered cars in my fleet.

 

[twX]

Thanks for your response, very informative. What sort of magnitude are you talking about for shorter OCIs? e.g. the 10-12,000km I'm doing now, or something closer to half that?

I'd go 5-6,000 km on your next OCI, then start extending it further if the UOA looks good. A TBN test might be helpful. If there's evidence of sludge, you might want to stick with shorter OCIs for a while to help clean things up.

I'm not actually convinced this is an oil temperature gauge, as it warms up at the same rate as the coolant temperature in pretty much every petrol & diesel car I've ever owned - and certainly far quicker than the oil temperatures in the petrol-powered cars in my fleet.

Yeah, oil temperature will normally lag coolant temperature by quite a bit, even if the engine has an oil-coolant heat exchanger. Some vehicles just calculate an estimated oil temperature instead of using a sensor.

 

[wavinwayne]

Thanks for posting. I have the little brother to your X5 engine in my 535d. Mine is the N57D30T1 twin turbo. I plan to do a UOA after this OCI, which should be about 5 months from now. I don't drive mine too hard; it's mostly driven at 75mph on the highway, 10-12 hours/week. It'll be interesting to see the results. Hopefully it'll be boring reading.

 

[more_fasterer]

I'd go 5-6,000 km on your next OCI, then start extending it further if the UOA looks good. A TBN test might be helpful. If there's evidence of sludge, you might want to stick with shorter OCIs for a while to help clean things up.

Great thanks, I'll give that a go.

 

[Marcozi]

Do you take many short trips (under 15 miles as it's a diesel)? The oil temp gauge is controlled by the engine computer (DDE in BMWspeak), so I wouldn't rely on it too much. I recommend you take a 50+ mile trip at highway+ speeds on a weekly basis. That'll burn off condensation and fuel in the oil.

 

[more_fasterer]

Yeah I don't have too much reliance on any temperature gauge fitted to a car from the factory, but this one seems particularly unrealistic!

Short trips < 25km are in the minority for this car. The most common distance travelled is in the 25-50km range with a long distance trip (100-600km) every month or so.