Sample from new 200 hour $300k excavator getting fuel from a local card lock station. Two mechanics headed out on a Saturday to diagnose, and they finally took a fuel sample

Fuel sample taken from bulk tank prior to starting Cleanboost regiment 

Fuel after 8 years treating each delivery adding Cleanboost to keep microbes (black slime) from returning.
​Fuel delivery driver stated guarantee water and microbes in each fuel delivery its the nature of diesel.
​The user has to take ownership of tank hygiene to keep the bugs away.