DiscussWorldIssues - Socio-Economic Religion and Political Uncensored Debate - View Single Post - It Looks Like The Missus And I Are Officially Going Green

**MontyP@thon** · 08-24-2012, 04:20 AM

That's probably the same as if you run 100% veg oil too, as when the ambient air is cold (in the winter) the veg oil or bio diesel congeals and you end up with your fuel system and probably your jets blocked with congealed oil.

My old Pug 306 Diesel could run on 100% veg oil, straight from the supermarket bottle, but that's because it had a Bosch fuel pump, other models of the same car used a Lucas pump and thus couldn't run with 100% veg unless they were modified with either a heater or some other means to stop the veg from congealing in cold weather and blocking up the entire system.

And even though my car could run 100% veg, I never bothered.

Actually, the use of Biodiesel in the newer TDI's is a bit more complicated than that.

The problem with BD is when used in combination with a DPF (Diesel Particle Filter). Every so often, the DPF needs to be regenerated. This is done by spraying a small portion of diesel into the cylinder during the exhaust stroke. The unburned diesel is carried to the DPF where it is ignited and heats up the DPF enough to burn off the stuff that's collected. The issue shows up during that post injection. Regular diesel has a lower evaporation point so it will vaporize almost instantly in the exhaust gas. Biodiesel has a much higher evaporation point and does not get vaporized. Instead, it ends up getting sprayed onto the cylinder walls and slips past the piston when it completes the exhaust cycle allowing a small quantity of BD to get into the engine oil. Over time, it begins to dilute the engine oil. This can be a concern since these engine are scheduled to have the oil changed every 10k miles.

If you want to run high % of Biodiesel in these engines, you really need to keep a close eye on your engine oil or change the engine oil sooner. Personally, I get a bunch of these when they are on sale for

08-24-2012, 04:20 AM	#51
MontyP@thon Join Date Oct 2005 Posts 523 Senior Member	That's probably the same as if you run 100% veg oil too, as when the ambient air is cold (in the winter) the veg oil or bio diesel congeals and you end up with your fuel system and probably your jets blocked with congealed oil. My old Pug 306 Diesel could run on 100% veg oil, straight from the supermarket bottle, but that's because it had a Bosch fuel pump, other models of the same car used a Lucas pump and thus couldn't run with 100% veg unless they were modified with either a heater or some other means to stop the veg from congealing in cold weather and blocking up the entire system. And even though my car could run 100% veg, I never bothered. Actually, the use of Biodiesel in the newer TDI's is a bit more complicated than that. The problem with BD is when used in combination with a DPF (Diesel Particle Filter). Every so often, the DPF needs to be regenerated. This is done by spraying a small portion of diesel into the cylinder during the exhaust stroke. The unburned diesel is carried to the DPF where it is ignited and heats up the DPF enough to burn off the stuff that's collected. The issue shows up during that post injection. Regular diesel has a lower evaporation point so it will vaporize almost instantly in the exhaust gas. Biodiesel has a much higher evaporation point and does not get vaporized. Instead, it ends up getting sprayed onto the cylinder walls and slips past the piston when it completes the exhaust cycle allowing a small quantity of BD to get into the engine oil. Over time, it begins to dilute the engine oil. This can be a concern since these engine are scheduled to have the oil changed every 10k miles. If you want to run high % of Biodiesel in these engines, you really need to keep a close eye on your engine oil or change the engine oil sooner. Personally, I get a bunch of these when they are on sale for
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