Not hypothetical at all!

The answer is yes, you can add additives meant for diesel to B100 or any other blend of biodiesel.

In some cases however, the additive is not as effective with biodiesel as it is with petroleum diesel, the main example being anti-gelling additives, some of which work OK on biodiesel, and others of which don't seem to work at all on biodiesel. However, none of them hurt.

I still add a bit of Powerservice to my biodiesel, especially when blending with petroleum in cold weather. It helps prevent the diesel portion from gelling, which in turn helps protect all the fuel, and you still get the cleaning and cetane benefits (though biodiesel doesn't need cetane raising as much as most petro-diesel).

In fact, I've heard that many additives actually use methyl esters (biodiesel) as an additive base! I don't know which ones, unfortunately.

If you are running biodiesel, you might find that you don't need some of the additives you normally use, like cetane enhancers, so give it a try without any additives for a while, but if you want to continue using them, it certainly isn't a problem.

peace,
sam

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"That f***in' biodiesel is makin' me hungry."

1982 300TD Astral Silver w/ 250k (BIO BNZ)
2001 Aprilia SR50 Corsa Red w/ 5.5k (>100 MPG)