300,000 mile report
 

Just got the '08 GL320 home from the regular 300,000 mile service. I have previously reported at 250,000 and 280,000 miles.

If it can be poured it was changed. If it filters, it was changed. The water separator was seeping a bit; it was replaced. There was a tiny crack at the inlet neck on the coolant reservoir, so a new tank was installed. A seal on the oil filter housing was leaking and due to a change in the part the old seal is not available anymore. So a new housing was installed. Several iffy looking hoses of one kind or another were changed.

It is interesting to me what has not ever been replaced: Front brakes. Ball joints. CV joints. Radiator. A/C system. Door handles (apparently a recurring problem for many). Starter motor. Glow plugs. Audio/video components. Shock absorbers (rear only). The Arnott air suspension parts have now lasted 150,000 miles with no indication of leaking. Oil consumption remains about 1 1/2 quarts between 10,000 mile oil changes and the fuel consumption overall continues to be somewhere north of 24 mpg.

I purchased this car five and a half years ago with 110,000 miles already on it. I have now driven it myself almost 200,000 more. The journey from 150,000 to 200,000 was by far the roughest stretch, with nearly $20,000 in repairs and maintenance in just 25,000 miles. These last 100,000 miles have been relatively untroubled. Total repairs, maintenance, tires and fuel have added up to an alarming $50,000 - or close to it. However, this works out to a total cost of operation of only 20 cents per mile. If I include the original purchase price it has cost about 36 cents per mile to own and drive, insurance and property tax excepted. I take some comfort in contemplating that, driving nearly 40,000 miles per year as I do, had I purchased one new the depreciation cost alone would have been about $50,000 in less than three years.

300,000 miles was my original goal; the car no longer owes me anything. I would consider myself satisfied with the purchase in every way were to go out in the morning and find just four rubber tires and a pile of rust. That said, there is no apparent downside to just driving the car another year, two years, three years ...? It has almost no resale value, but the appearance is still excellent as is the performance. And I still really like the comfort and utility.

OP, I was going to say that you are an anomaly getting 300k out of your OM642 motor, but then again you've fixed what typically kills these engines - the oil leaks.
Obviously at great cost. Well done, keep on keepin' on.

I think several things are working here. He notes that the car has original front brake pads which at 300k tells me he is all highway miles which these engines love. Leaks are not a big deal, just gotta stay up on them. I have 140k on my 2011 and it runs and drives like new however I have had a good share of repairs as well (some are things like Airmatic replacement which are time dependent). I am sold on the OM642 despite the ragging it gets by some. I have owned 3 of them and they just need TLC.

It's also is a plus that it's not a 350 with Adblue system. Owning a 320 and not a lot of short trips seems to be the key if you want to own a diesel GL. Even then, still not cheap to maintain and repair. The fuel efficiency helps though.

My GL450 has been around $0.30 per mile to operate including the cost of the vehicle, fuel, maintenance, and repairs but not including insurance. I've owned it since 2007 and put all but 1k miles on the GL.

With that said, I can guarantee the next 50k miles will be more expensive than the 320's since my GL has signs of the dreaded balance shaft sprocket failure. A used 550 engine installed will run around $5k but could DIY for less than $2k. So far, the car has been ultra reliable and parts have been dirt cheap to maintain and repair. The engine will be my first big out of pocket repair other than the AC compressor I just had changed. Could have done it much cheaper but I needed it quickly and paid the price. It also helped that I had a 100k mile warranty that covered a bad water pump, struts, trunk latch, folding mirror, and turbine speed sensor/valvebody in the transmission.

Absolutely agree on all parts. I'm on my second set of rear shocks since the factory ones were changed. Change them, there is no way they are still good. It will really improve your handling and comfort.

When two of your last 4 cars have ABC, Airmatic is a dream to maintain and dirt cheap. Even without making the ABC comparison, I like Airmatic quite a bit for handling and ride comfort and, again, it's not expensive to maintain nor is it problematic if you watch for the warning signs and repair before the issues get worse.

I agree. We have a 2012 GL350 and have 70k miles on it. Last time I dropped it off for service, I got a 2019 GLS 450 as a loaner. It was slightly quieter than our 2012 (and had a slightly better ride). It also had a better backup camera. Other than that our 2012 drives like a new GL (which, well optioned ones, nowadays costs around $100,000). Diesels do have some specific issues, but so do GL 450's and 550's. I don't think any GL classifies as very reliable. They are incredibly comfortable though. We tow a 6000# camper and I love the low end torque and the great fuel economy of the diesels. The engine rarely screams (like gas engines) and it has great range (don't have to stop often to refuel). We put around 10k miles on our GL each year. If we get to 150,000 miles (should take us another 8 years to get there), I'd be very happy.

field data suggests average lifespan of the om642 is just about 500k miles with some examples lasting much much longer.