So, I bought my wife a brand new 2006 VW Jetta TDI last year and wanted to share my experiences with using a diesel. One of the reasons we bought a diesel is so we can use biodiesel, plus I want to switch to a waste-oil system when the car is paid off. (On a side note, buying cars in Hawaii is a joke. Even though we were able to talk the dealer down nearly $3000 from the original price, we still paid more than $2000 more than the “street value” as listed on several car shopping sites).
We use 100% biodiesel in our car. For those who don’t know, biodiesel is made from recycled vegetable oil, which isn’t really that strange. The original diesel engines were made to run on peanut oil, if I remember correctly. And even though nearly every diesel car maker states you can void your warranty if you use anything greater than 5% biodiesel blends, it’s mostly a lie.
Biodiesel is a fantastic solvent so if you have an older car, it could conceivably eat through your rubber hoses (just like petroleum jelly on latex condoms). However, the newer cars use synthetic rubber or otherwise solvent-resistant hoses so you really shouldn’t have a problem with it. Additionally, the solvent action can clean out your gas tank and other car parts, effectively scraping off any particulates that settled out of regular “dinodiesel”. This dislodged material will then flow through your engine and can gum it up, though most of it will be trapped by your fuel filter. If you’re switching from dinodiesel to biodiesel, be aware that you’ll have to change your fuel filter fairly frequently for the next few months. Also, be careful spilling the biodiesel on your car; you can strip the paint if you don’t wipe it off quickly.
Though there isn’t a federal regulation (yet) for biodiesel quality, there are the ASTM preliminary standards. These standards classify the different amounts of glycerin, water, sediment, etc. found in biodiesel. Your biodiesel supplier should provide you with the latest results of these tests; if they don’t, you probably don’t want to use their fuel.
You can mix biodiesel with dinodiesel (hence the 5% blends often found in the US). You can also use either one as needed, such as driving cross-country when you have to use truck stops for fuel. However, you don’t want to switch your tank from one to the other. Switching between the two can lead to your fuel lines, gaskets, etc. leaking and other problems due to the dissimilar properties of each fuel. It’s okay to switch, just make sure you use the same fuel type for a few fill-ups before you switch again.
In place of biodiesel, you can use waste vegetable oil (WVO) or straight vegetable oil (SVO). SVO is regular cooking oil while WVO is used cooking oil. To do this you have to spend roughly $1000 changing your engine to handle the higher glycerin amount in the oil and adding a heater to lower the viscosity. But doing this means you don’t have to hunt for a biodiesel dealer or mess with the chemicals to make your own.
On a final note, ethanol isn’t the great gas saver popular media portrays it as. Consumer Reports did an investigation a few months back showing that your mileage actually goes down when using ethanol and ethanol-blends. This is because ethanol simply doesn’t provide the same power output as gas. Plus, ethanol is being pushed by the corn lobbyists to keep the corn subsidies rolling in while keeping the cheap ethanol from other countries out.
Personally, if I was going to use alcohol in my car, I’d set up a methanol still and just use food and yard waste. It’s cheaper and you can get it for free; just have your neighbors drop off their waste. Hmm, sounds just like getting free used vegetable oil to make biodiesel.