There might be components of pump Diesel that the IP needs to stay healthy. The IP is basically lubricated with engine oil but the innards that contact fuel directly might be lubricated by pump Diesel and insufficiently so with soybean cooking oil.

What concerns me about soybean cooking oil is that the funnel I used to pour soybean cooking oil into the SDL had some sort of formation that was difficult to clean off. I'd be concerned with the same formations if I were running straight soybean cooking oil. It could just be dust settling on residual oil but those were darn nasty clumps.

Maybe keeping a mix of pump Diesel isn't a bad idea to keep these potential problems at bay.

Sixto