Thanks for your post. It corroborates the consensus one finds reading German wvo sites: a much simplified approach i.e. minimal modifications - and more mere reliance on the stock set up of the car to be able to deal with the vegetable oil. Counter-intuitive considering the German penchant for over-engineering.

Although, as you state, "even at hot summer temperatures, at a cold start the engine is always running shaky blowing blue smoke out of the exhaust" would suggest that the incomplete combustion taking place under those conditions could lead to unwanted deposits (coking),leading to problems in the long term.

Perhaps this is offset by the (very) high speeds and predominantly autobahn driving that you guys do over there compared to type of driving done here in the US, which allow your cars to run cleaner and not end up being affected by coking which gets burned away?

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'83 SD, 2x '85 SD
You are entitled to your own opinions, you are not entitled to your own facts.