I think you mean, convert a car that uses an auto tran to run on veggie oil. Yes, both manual and auto trans cars can be converted to run on veggie oil. I would personally choose to run biodiesel since it's a better fuel.
The transmission itself must use the correct lubricant, the manuals use gear oil, the autos use auto transmission fluid.
Who told you that? Both manual and automatic transmission TDI can be converted to use veg-oil. Many people run into serious problems using veg-oil, if I were you, I would look into biodiesel, see the FAQ section at the top for some introduction to biodiesel information.
IMHO, veg oil is just too thick for a TDI, even when heated. There are too many reports of problems that I would not convert a TDI to veggie. It' not a Mercedes, it's not a diesel truck, it's a light duty VW.
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