Really?? Depending on the feed stock, it may have a higher flash point than dead dinosaur juice (diesel) - but it will certainly make the fire hotter if ya spray some B100 on it. A 1200*F exhaust manifold will be well above ignition temperature of any bio-d - no matter how ya make it! Please be careful.

Luckily, there is nothing to fear. The factory fuel lines should last as long as they would have - as long as you never allow bio-d on the OUTSIDE of them. That goes for heater hoses, vacuum lines and everything else made of rubber under the hood.

On a side note, there is finally a fuel stabilizer for VO-based fuels. This stuff should extend the life of VO and B100, preventing oxidative polymerization that leads to short filter life and build-up in fuel tank, lines and even engine heads/injectors. http://www.frybrid.com/vegstable.htm