It's mostly a myth
http://www.cartalk.com/blog…
TLDR: And normally, no permanent damage is done to the injectors, the seals or anything else. And because the car won't actually run on diesel fuel, there's little risk of damaging the catalytic converter.

Yeah, especially since Gilfoyle explicitly mentioned their lack of competition right at the end of the previous scene

"Приговор смертная казнь оставлен без изменения и будет приведен в исполнение в ближайшее время."
в ближайшее время ~ in the near future
doesn't really mean immediately.

Not exactly: M-DISC https://en.wikipedia.org/wi… claims lifetime of 'up to' 1000 years.