it just all smoke and mirrors?

I’ve been working on my son’s 2L turbo charged 4 cylinder diesel SUV that is built to meet the Euro5 emission standards.
In order to meet the emission standards called for by Euro5 , the engine has a turbo to boost air inlet pressure, a charge air cooler to cool the air leaving the hot exhaust gas driven turbo, an exhaust gas re-circulation control valve (EGR) that directs some of the exhaust gases back into the inlet manifold after they are cooled, an oxidation catalytic converter to treat exhaust gases before they enter a diesel particulate filter (DPF) located at the exit of the exhaust piping system. The DFP is the last trap for particulates before the exhaust gases leave the vehicle.

Additionally the engine must use (in this case about 10L) of very low ash, so call, ECO engine oil. These items are provided to meet the low NOx and CO2 provisions of Euro5.

All this is good stuff only if it all made sense. This is what I mean.

  1. The engine oil used goes into the engine clean and after a few thousand kilometers comes out BLACK with soot. The oil is captured, hopefully recycled, and then, for 80 to 90% of it, burnt (depending on the combustion temperature and burner efficiency) to NOx, CO and CO2 in waste oil burners to recover the heating values in the oil.
  2. The EGR system ‘self clogs’ and although not on any documented maintenance schedule, requires frequent unclogging. Typically this requires both chemical and mechanical processes to keep the valve working correctly and to prevent the vehicle from stopping without warning. The collected soot/tar like accretion is ‘disposed of’.
  3. The DPF captures particulate matter and if the car is not driven for extended periods at highway speed, clogs up and the vehicle stops. When it is drive ‘as required’ the system burns out the clogged matter presumably to some NOx, CO and CO2.
  4. Filters on the system (oil, air, diesel) also collect ‘materials’ that are disposed of and in the most part they go out with the filter when it is changed.

My point? At the end of the day the vehicle stops operating when all the recycle streams are not allowed to leave the system. To keep the vehicle running by one means or another they do leave the system and in the main they end up as varying amounts of CO2, CO and NOx.

Maybe Euro5 is just all smoke and mirrors?


It just sounds like a pollution delay system to me!


A little like dual flush water saving toilets that require 3 flushes to evacuate!

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We’ve all had to jump on the diesel bandwagon, there’s no alternative in certain vehicles.
It’s going to come back and bite us, that’s for sure.
People are already posting online how to block off the egr valve.

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Being an oldie who mainly drives short distances around town when an engine barely warms up a diesel makes no sense, so those “no alternative” vehicles make no sense either. As the population ages perhaps the market will speak more loudly, and/or diesel technology will rival petrol for short start-stop trips.

I agree. I think it’s ludicrous that a small sedan which is more than likely only a city car is offered in diesel. Dearer to buy, dearer to service and the fuel stinks. Some people only buy diesels for the fuel economy, not taking into account other costs.

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Or perhaps as more electric vehicles enter the market at more cost points they will rival petrol, gas, and diesel for the short start stop trips and the longer traverses of our great country. Here is hoping!


Your particular situation is very well described. It is left up to the manufacturers how they will comply with the various standards. There is no mandatory fitment of certain devices or treatments. While there is some common features with manufacturers to fit devices to comply, the choice is up to the manufacturers. I am aware of the setup you describe. It is cumbersome and open to breakdown and abuse. Other manufacturers have come up with simpler systems that are effective, should last and be less trouble than your situation. Doesn’t help us as consumers as we get to find out after the event.

My experiences are quite the opposite, @slf. Even my largest solid waste movements are easily flushed with the ‘half flush’ button. Even placing a full bottle of water in the cistern to displace 600mL of water from each flush doesn’t make the flow weak enough to clog up my movements. Maybe you have an old toilet system?