Diesel in engine oil - long term, should I be concerned?
Discussion
I bought a new, diesel engined vehicle 2.5 years ago. It's one of this manufacturer's first attempts at DPF technology. Rather than install an extra injector in the exhaust to add the extra diesel for a regeneration of the DPF, they just add more fuel in via the main cylinder injectors (and you hear the engine noise change when it's doing it).
In addition to this, the ECU had a very aggressive regeneration program - it would regenerate the DPF more frequently than every 100 miles. At best, on a long motorway run, it'll be around 100 miles per regen. The result of these two factors means a significant amount of diesel gets past the rings and ends up mixed in the with engine oil. Apparently, some people have had this get so bad that the engines have ingested the oil via a breather and self destructed!
Of course, the manufacturer and dealers are keeping quiet about this issue. I noticed early on that I couldn't seem to get an accurate reading off the dipstick - it was way above the max mark, and I just assumed it was due to the convoluted dip stick route smearing the oil around.
The service interval is 12k miles, and at my 24k service they quietly made some changes to improve the issue. There was an ECU update to reduce the frequency of regenerations (probably about 150 miles at best now), and a revised dipstick that has 3 marks on it: min, fill max, and an absolute max (which is about 2 inches higher than fill max). I guess their thinking is that the oil level shouldn't reach the absolute max in between the 12k services.
But what are the likely long term effects of significant amounts of diesel diluting the engine oil? Am I worrying over nothing?
In addition to this, the ECU had a very aggressive regeneration program - it would regenerate the DPF more frequently than every 100 miles. At best, on a long motorway run, it'll be around 100 miles per regen. The result of these two factors means a significant amount of diesel gets past the rings and ends up mixed in the with engine oil. Apparently, some people have had this get so bad that the engines have ingested the oil via a breather and self destructed!
Of course, the manufacturer and dealers are keeping quiet about this issue. I noticed early on that I couldn't seem to get an accurate reading off the dipstick - it was way above the max mark, and I just assumed it was due to the convoluted dip stick route smearing the oil around.
The service interval is 12k miles, and at my 24k service they quietly made some changes to improve the issue. There was an ECU update to reduce the frequency of regenerations (probably about 150 miles at best now), and a revised dipstick that has 3 marks on it: min, fill max, and an absolute max (which is about 2 inches higher than fill max). I guess their thinking is that the oil level shouldn't reach the absolute max in between the 12k services.
But what are the likely long term effects of significant amounts of diesel diluting the engine oil? Am I worrying over nothing?
The mazda 6 I had dumped excess diesel from regen into the oil. The dipstick has a min, max and an X some way above the max. The handbook says to change the oil if it gets up too the X. So mazda obviously factor into it running with some diesel in the oil and it being safe up too the X point.
Zoobeef said:
The mazda 6 I had dumped excess diesel from regen into the oil. The dipstick has a min, max and an X some way above the max. The handbook says to change the oil if it gets up too the X. So mazda obviously factor into it running with some diesel in the oil and it being safe up too the X point.
This is exactly what they have introduced with the 'upgraded' dip stick. But the fact it wasn't there from the start suggests they never planned on this scenario, just reacted to it. Which is a bit of a worry. For all I know it could be consuming oil as well, and the level still going up, which could mean a lot of diesel and heavily diluted oil. I mean, even with the best oil control you'd still expect an engine to get through half a litre or so of oil in 12k miles.It doesn't sit easy with me knowing the oil is constantly contaminated in this way, but not sure if/how to raise it with the dealer? There's no problem with the engine yet, and lets face it, it's quite likely to be well out of warranty when the issue does finally cause a failure. I guess the only thing I can do to minimise the risk is to perform more regular oil changes, say every 6k miles instead of 12k. The main dealer charges £200+ for doing an oil change, and if I got it done elsewhere, it wouldn't surprise me if they tried to wriggle out of the dealer warranty (5 years).
The other concern is that such regular regeneration cycles are causing unnecessary wear on the DPF itself. I guess a DPF removal would cure both issues, but then the problem with that is emissions & MOT compliance, and definitely forfeiting the warranty!
Quite apart from the problem you're having, I just regard it as good practice to change the oil and filter on anything turbocharged ( which I'm assuming this is ) at 5k miles, the heat generated by a turbo, and 15k mile service intervals, doesn't sit well with me. Done this for years as a safeguard on everything turbocharged I've owned. Recommended service intervals on modern stuff's a joke.
I'm gonna take a stab at yours being a Mazda.
Sits back and waits to get shouted down!
I'm gonna take a stab at yours being a Mazda.
Sits back and waits to get shouted down!
ShiningWit said:
What a crap design feature, sell it and buy a petrol powered car.
No one sells a petrol engined pick up in the UK, and since the diesels only get 30mpg, a petrol one would be really thirsty! Plus the low revving high torque engine suits the vehicle. All my cars have petrol engines though.Selling it at 2 years old doesn't make much financial sense. However, when the warranty runs out, the potential cost of a bottom end rebuild is going to be a factor.
mjb1 said:
No one sells a petrol engined pick up in the UK, and since the diesels only get 30mpg, a petrol one would be really thirsty! Plus the low revving high torque engine suits the vehicle. All my cars have petrol engines though.
Selling it at 2 years old doesn't make much financial sense. However, when the warranty runs out, the potential cost of a bottom end rebuild is going to be a factor.
Ah fair comment, I assumed it was a car Selling it at 2 years old doesn't make much financial sense. However, when the warranty runs out, the potential cost of a bottom end rebuild is going to be a factor.
It just goes to show how the manufacturers are struggling to make diesels work within the new regs though, it looks like pure desperation.I have a customer with a fleet of vans that do this and one went bang followed by a big hoo ha over who was responsible . He had to pay to get the van earning again so what we do now is have them in mid service interval and suck half the sump contents and replace with the correct spec then change the lot at the normal interval . Not scientific these were adding 1-1.5 litres over 8000 miles .
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