Klay;
  Luckly  we  do  not  have  many  of  these  cases  anymore,although  we  have  had  a  number  of  "burnt  up"  motors  that  the  owners  claim  are  from  vandalizm,putting  sugar  in  the tank. We  always  take  a  fuel  and  
oil  sample  and  have  them  analized. We  have  found  many  many  foriegn  chemicals  in  some  engines  and  have  denied  the  claim  based  on  that....  Not  trying  to  screw  anyone  out  of  anything,but  when  you  find  all  kinds  of  household  cleaning  fluids  in  the  fuel  and  
oil,well,  you  get  the  drift,and  anyway  "intentional  acts"  are  an  exclusion!!!!!!!!!!!!!
  I  have  had  a  few  cases  of  sugar  with  the  newer  fuel  injected  autos  and  we  also  have  them  flush  and  clean  out  the  fuel  injectors,just  for  a  safety  measure...
Now  when  you  have  sand  in  the  
oil  as  I  have  seen  a  few  times,that's  bad  news..... You  should  see  the engine  block  after  running  100  miles  with  what  we  believed  to  be  about  a  pound  of  sand  poured  into  engine  from  the  oil  fill  on  the valve  cover.... Not  much  left  to  call  piston  rings  and  a  cylinder  walls  soo  scoured  you  would  not  believe  it... Chaulk  it  up  to  a  jealous  boyfreind  or ex-husband,but  sand  is  bad  news....
Ron;  Never  seen  sugar  in  the oil,but  surely  would  beleive  it  would  "gum  up"  and  very  possibly  clog  the  oil  pump....  When  we  mixed  sugar  and  oil  at  room  temp,it  got  very  thick  and  flowed  about  like  molasses. Untill  the   engine  warms up  and  thins  the  oil  it  could  very  possibly  clog  oil  passages  and  the  oil  pump  causes  the  engine  to  starve  for  oil  and  damaging  it in  the  process....
BTW; John  Force  ran  an  additive  in  his  fuel  on  his   funny  car  for  a  couple  of  years  when  he  was  sponsored  by  a  candy  manufacter,made  the  exhaust  smell  just  like  the  candy!!!!!!!!!!!!!
David