Dear Sirs:

To clear up a misconception about bio-diesel, although it comes from biological sources - that is, plant, vegetable, or even animal fats, properly made bio-diesel, (usually methyl-esters) does NOT gel - (hindi nagsesebo).

Why?

That's because the process of its manufacture is akin to soap-making.

The dried, strained and filtered bio-oils are heated and then carefully mixed (in the right proportions) with a methoxide - a mixture of a strong base (usually sodium hydroxide - i.e. caustic soda) and anhydrous (water-free) methyl alcohol (methanol).

This causes the gel-forming materials in the oil to separate out, forming layers of treated bio-diesel on top, followed by layers of glycerin and soap on the bottom.

The resulting product must then be washed and dried.

The more dirty and contaminated the source oil is, the more methoxide is needed to treat it and the more glycerin and soap will form.

That was the whole purpose of the process - to remove the less desirable parts of the bio-oils. In fact, too much sodium hydroxide will convert almost all the oil to soap - think PERLA.

However, it does not mean that untreated, straight vegetable oils (SVO's) CANNOT be used as a diesel fuel, indeed they can, its just more likely they will form gums, varnishes and gels in your engine when it gets too cold outside.

Of course that problem is more serious in cold countries, like Europe and America, than here in the Philippines - except maybe if you live in Baguio.

Another thing to remember is that although these parts of the bio-oils tend to clog the fuel lines and filters of your engine, they have the beneficial effect of increasing the fuel's LUBRICITY - its ability to lubricate the parts of the engine it gets into contact with.

That means they help prolong the life of your injector nozzles and injection pump, by causing less wear and tear.

A cursory examination of the many technical papers openly available on the internet will indeed confirm that a little bit of bio-oil helps boost the lubricity of even a marginal petro-diesel by a large amount.

So ironically, converting Straight Vegetable Oils (SVO's) to bio-diesels improves their FLOW properties, but REDUCES their lubrication properties!

It also removes a significant proportion of the total burnable materials in the bio-oil itself.

Thus making bio-diesel from bio-oil makes the product cleaner and more free-flowing but sacrifices a lot of lubricity and some of the energy-making potential in the fuel.

Hope this helps,

Best Regards,

Dusky Lim

P.S. - I do in fact make, use and sell a diesel fuel additive, which I recommend for mose older (pre-CRDI) engines it helps improve power and economy and reduces a lot of the black smoke.

Please PM me if you're interested.