My Opinion.
I have been in the DIESEL FUEL INJECTION industry on all levels for the previous 18 years, I served my time as an apprentice with Lucas Service back in 1988. During this time I have gained a massive amount of knowledge and experience in this industry and all of the associated products and problems.
I now work for a major diesel fuel injection manufacturer as an Assistant Development Engineer.
There is not a lot I do not know about Diesel FIE (Fuel Injection Equipment)
Well, In relation to this argument I do know the FIE will not stand anything with less lubricity than diesel.
It will not stand any solutions which are water based, FIE will not tolerate any water content above 2%.
But to me, the main player in FIE failure is fuel which has particulate contamination or “Dirt”.
Yes the filter should remove any particles above 2µm however, modern common rail systems run with clearances between moving parts of less than 2µm, so any dirt the filter fails to remove can then access a particular clearance which is larger than itself.
Remember, u cannot get a 3µm “dirt” particle into a 2µm gap.
So if your running clean (no water or dirt) diesel and changing your filters regularly, there should be no reason why your FIE should fail.
Fuel Options Available:
Three way mixer valve kits (veggie oil)
Mixing Diesel with Veggie oil (veggie oil) Diesel adds the lubricity and helps the burn.
Bio Diesel (processed veggie oil) Diesel Substitute.
RVO (recycled veggie oil) if not done properly will end up dirty.
SVO (straight veggie oil) clean oil but not as cheap,higher water content and will go off over time.
Three way mixer valve kits : Cost between £400 and £1200. These systems generally use a 3 way valve to electronically switch from diesel to oil depending on the temperature of the engine etc.
They also utilise a heat exchanger to warm the oil up before it reaches the pump. And two tanks.
THESE SYSTEMS ARE FUNDAMENTALLY FLAWED!
I can say this because I know, lets look at the circuit diagram for a diesel engine:
Tank >> Low Pressure Filter >>> Low Pressure Pump>>> Injector Pump>>> Injector Pipe>>> Injector>>>Combustion Chamber
The reason why I have blued some of these words is because at low ambient temperatures these are the areas that will suffer the most in terms of freezing.
Now lets look at what the 3 way valve system does to these area’s when the car is cold.
Tank >> Low Pressure Filter >>> Low Pressure Pump>>> Injector Pump>>> Injector Pipe>>> Injector>>>Combustion Chamber
ABSALUTLEY NOTHING !
This is because they rely on a heat exchanger to heat the supplied fuel, the heat exchanger does not get hot until the engine does, this is the reason they run on diesel when cold and your supposed to run on diesel for a few minutes before turning the engine off.
Now to make sure this system is free of veggie oil before you switch your engine off would take approx: 10 minutes of running at half speed. This will no doubt use a lot of diesel giving you less MPG..
And even if you switch from diesel in the morning (presuming you have cleared the pipes of oil the night before) then the only oil which is going to be defrosted enough to use, is the oil in the exchanger, this is usually miles away from the pump so you still have to defrost the fuel lines to the switch and even the switch.
One other thing these systems do not do is switch the return to tank. A fuel pump will not utilise all of the fuel in it, in fact it runs mostly on the fuel supplied but then re circulates a lot of the fuel in order to lubricate the rest of the moving parts. When it does this it returns some of this fuel (and also some of the fuel from the injectors) back to the tank.
If you do not switch this return feed at the same time you switch the supply, then you are not separating the two different fuels, but mixing them.
My Conclusion:
Using cheap, used veggie oil from the chippie is dangerous if you do not follow the cleaning process precisely.(most of the scare mongering comes from people putting any old rubbish in and expecting their car to run fine)
Most mixing valve systems available, are just very expensive mixing machines, if they do not handle the fuel system and not just the supply.
If your car breaks when running clean veggie oil or bio diesel then it was probably going to break on normal diesel.
If it breaks on dirty veggie oil……tuff you should not have been so tight.
Safest Method: (recommended)
Use Bio Diesel Alone
Or
Use clean untarnished veggie oil of cooking grade quality….mix it in small amounts with your diesel, 5%, 10%, 15% etc until u notice a problem.
If no problem materialises then keep going until your at 90% oil and 10% diesel. (the diesel will keep the lubricity correct)
Be wary of outside temperatures when running a mix and if necessary change to suit.
Change fuel filters 50% more frequently than before.
Do not use veggie oil which has been stored for more than 3 months.
Keep on top of your oil and general engine maintenance.
Change your batteries the offset if they are more than 2 years old
Renew your heater plugs before the winter
Spend the £400 you would have used on the kit and get an experienced fuel injection engineer to service or overhaul your pump and injectors.
If possible fit another return to tank filter and a water trap.
If you have any questions, queries or problems call me on 07719774665
Or your local Diesel Fuel Injection Specialist