Bio-diesel vs Petro-diesel - any experiences?

[ProfJohnL]

Just for general information I thougt I relate my experience of trying Bio Diesel rather than petrodiesel.

A local depot has started to sell BioDiesel, with claims of it being up to 25% cheaper than normal petro-diesel., @98.9p per litre. Well apart from the cost claim which is only about 18% cheaper than other local filling stations, I thought Id do some research and maybe consider trying it.

There are two quite polarised views about Bio-diesel if you look on the web, predictably those who make and sell the stuff, and conventional petrol heads.

It seems that there are several grades of Bio diesel, B5, B10, B20 all the way up to B100. The figures represent the percentage of the Biomass diesel in the mixture, the remainder is conventional fuel.

Now the buyer has to be aware, because some outlets do not make it clear what grade their fuel is, and unless you ask you may be supplied any of the mixtures above. There is also another important factor, and that is bio-diesel is not compatible with some engines. Typically any vehicle manufactured before 1993 must not use Bio diesel, as the fuel will quickly rot through any of the rubber based piping and seals in the fuel system, and there are some other mechanical reasons that makes then less suited to the new fuel.

Later cars had to be fitted with different rubber compounds that were more tolerant of the fuel. (there is a small amount of Bio-diesel already mixed with normal diesel as part of the petrochemicals bit to go 'green')

I run a Saab 9-3 2.2Dit diesel (GM 2.2 engine), , It is not the most refined engine, but it does give the vehicle a respectable performance, and reasonable fuel economy. Having been manufactured in 2001 it should be safe to use Bio in it. I went for the plunge, in a tank that holds 70Ltrs I had it brimmed with just 48 litres of B100 that gave me about a 60% mixture of Bio.

It took a few minutes of driving to become aware of any differences, and I have to report that I found some marked changes.

Acceleration performance is much worse. Previously accelerating from 40 to 50 in 5th gear would take about 5 seconds, it now takes 12 to 15 seconds.

There is marked lack of power at low RPM,

And fuel consumption has dropped from around 44mpg down to 40 and is still showing signs of dropping further.

I dread to think what the cars performance will be when if I tried to tow. I think it would struggle on Bio, where as it is more than acceptable on petro-diesel.

I can full understand that different engines may be able to extract more from the Bio diesel, so I would be interested to hear of other peoples experience with it.

 

[Philspadders]

be careful , very careful with bio diesel. Many modern engines can not deal with the levels of methanol that can occur in bio diesel, these methanol levels are not shown anywhere.

I driv a kia and the max % bio is 5.

 

[seth1]

I am surprised reading this,as i would think pre 1993 engines would be far safer to run on this type of fuel as most were non EDC equiped.As Philspadders says beware is an understatement,we found that on test the bottom 15% of a tank of fuel,and admittedly some tanks were 1000litres was infact water.It cost the same engine maker thousands in warranty claims which incedently is still going on.

The maker chose to spec the industrial engines with Bosch EDC15 which is better known as common rail,the same version fitted to most cars we drive.

John(prof) the best advise i could offer you is fill up with non Bio,Bosch VP 44 fuel pumps have a known history of failures,due to internal timing sensor and hall sensors being destroyed by bad fuel.

(corrosion)

 

[ProfJohnL]

Thank you both for your comments

It just goes to show that there is a lot of information out there, and it can be difficult to get to the truth of the matter.

I have already decided that Bio is not for me, at least in this car. I got further evidence of the lack of power to-day. On a trip to my mothers birthday celebration, I had to negotiate a hill, which normally I can climb in third gear. I had to drop to 1st to begin the ascent, and at best could only get into second.

I will be refilling with Shell V-power to rebalance the mixture.

 

[david_374241885]

My brother inlaw is a mega mileage van driver and says that cheap diesel is rubbish .And that Shell diesel is by far the best for sweeter running and MPG he and most of his van driver friends will not use anything else.

 

[ProfJohnL]

My brother inlaw is a mega mileage van driver and says that cheap diesel is rubbish .And that Shell diesel is by far the best for sweeter running and MPG he and most of his van driver friends will not use anything else.

Thank you David for your comment.

There has been a choice of petro-diesel grade for some time now, mostly preceding the wide spread availability of Bio Diesel, so I do wonder if your comment refers to the cheaper petro grades rather than the Bio diesel.

I do concur (or at least have convinced my self) that the is a difference between Tesco and other supermarket diesels. Interestingly in my area Tesco is not the cheapest so you cant always go by cost.

I have also convinced my self there is also a noticeable difference between the normal and the premium grades from the the major brands.

Its a close call whether the economics of the premium grades is fully offset by any improvement in MPG, but other factors such as smoother power delivery and running may convince you they are better for the engine and may reduce the wear and tear on the components.