Did mix vegetable oil with the Diesel in a VW Golf in the 90s, and it worked fine for years.
The french fries smell from the exhaust was a bonus.
Assuming that that’s a diesel engine car, it sounds like you can get away with mixing some sunflower oil into diesel for a short time, though it’ll create problems.
This talks about issues that came up in using a 50% blend of sunflower oil in diesel for two months.
https://library.ndsu.edu/server/api/core/bitstreams/1b185dd3-8962-4ce6-a192-2b9c8a206e4e/content
Long Term Performance of a Sunflower Oil/Diesel Fuel Blend
If you want to run veggie oil through a diesel they make kits for it. The fuels aren’t mixed, but pretty much any diesel can run on cooking oil provided it’s warm and clean enough.
The headline confused me, because I’m used to sunflowers being an euphemism for dead Russians.
The relationship between Russians and sunflowers appears to be one of give and take
