obwohl ja schon mehrmals diskutiert, möchte ich wegen diesem interessantem Thread und ansch. vielwissenden Schreiber das Thema nochmal anstosen. zumindest weiss ich jetzt welches der unterschiedlichen 2-takt-öle das passende für CRD-Motoren ist - Jaso FC.
gefunden im SA-Forum:
http://www.4x4community.co.za/forum/sho ... hp?t=68220
This has in the last two years gained a lot of momentum in Germany, after they started mixing 5% bio diesel with the normal diesel fuel. Now bio diesel in Germany is a mixture of raps seed oil and ethanol. This makes the concoction hygroscopic, i.e. it will absorb moisture (water!!!).
You now get an idea why there is such a high failure rate on VHP pumps and injectors on CRD engines in Europe.
This whole concept of mixing 2-stroke oil with diesel is nothing new. It started in Scandinavia and Northern USA among the fishermen' fleets in Winter.
But in our south african context, we first have to get a proper understanding about the quality of diesel:
1. Normal diesel is 500ppm sulphur content - Cetane - lower
2. Premium diesel is 50ppm sulphur content - Cetane - higher
3. "African countries diesel (Sadec countries and further north) can be anything up to 8000ppm sulphur content
If we now go back to the olden days of 10-15 years ago, it was not uncommon for diesel in SA to have a 3000ppm sulphur content. In those days one had to change the oil every 5000km as otherwise one ended up with a jelly like substance in the engine, also called the black death or sludge.
I am now going back to the topic at hand. The highest cetane rating in SA diesel is found in the Sasol 50ppm diesel. This 50ppm diesel (irrespective of brand) also has a reduced lubrication property which leads to defective injectors, see for example Toyota 3 litre bakkie engines.
In two-stroke oil we get 4 different quality ratings, which are based on the JASO (Japanese Automotive Standards Org.) scale:
JASO-FA very basic single grade SAE30 or SAE40 based 2-stroke oil (premix only)
JASO-FB Used for most premix industrial 2-stroke engines and scooters
JASO-FC "Low ash burn" used for separate oil injection and most outboard motors. this oil can be mineral or part synthetic
JASO-FD This is fully synthetic 2-stroke oil for racing engines. It is not suitable for mixing with diesel, because a) too expensive and b) not compatible with cats and particle filters.
For All Series LR and Disco1 and 2 a Jaso-FB rated oil is fine. For Disco 3 and 4 a JASO-FC rated oil has to be used, such as the Fuchs oil.
Now in order to provide better lubrication but at the same time also better power delivery from the engines, the ideal solution seems to be to add 2-stroke oil (see above) in a mixing ratio of 1:200 i.e. 500ml per 100lt diesel.
This will increase the cetane rating by 3-5 points and will provide the following benefits:
1. Much better and more complete combustion (lower EGT)
2. Self cleaning of engine internals, as JASO-FC compliant 2-stroke oil burns cleaner and better than diesel. Due to this there is also about a 3-5% gain in fuel economy.
3. Sufficient lubrication of high pressure components in the diesel injection system.
4. Much quieter starting in the morning and smoother running
5. Reduced smoking
6. In engines with particle filter "burn free" action is reduced from every 600-700km to between every 1200-2000km
7. Much lower "clowd content" of diesel exhaust fumes typically from 0.95 down to 0.47. This is measured in Germany at the TüV.
8. Large government fleets in Germany report fleet reliability (MB Cdi, BMW CRD, Audi Tdi etc. etc. to exceed 400'000km WITHOUT VHP pump or injector failures
