Once upon a time, there was a guy who delivered pizza for a living.
His boss didn't want to pay a mechanic to maintain the delivery
car, so told the pizza man to do all the routine stuff himself.

The boss also owns the garage next door.  He told the mechanic
"This delivery guy needs help with his car sometimes.  He is going
to do all the maintenance, but I want you to step in and help when
he has problems.  We'll save money that way."

Over the next several months, the pizza man put gas in the car
just fine, but he didn't change the oil on schedule, so the car
had excessive wear.  The car started performing poorly, so he
took it to the mechanic, who changed the oil and put in oversize
pistons to compensate for the wear.  He told the pizza man
"Listen, you have to change the oil".

When it was time, the pizza man changed the oil, but he poured it
into the automatic transmission fluid inlet by mistake.  Then he
drove off without any oil, whereupon the insides of the engine
melted and the car came to a screeching halt in the middle of the
highway.

The pizza man thought this was odd, so he got a new battery, but
he installed it backwards.  The car wouldn't start, so he
adjusted the gap on all the spark plugs and cleaned the points.  That
didn't help.  The headlights still worked, though.  So, he called the
mechanic and said "Help! My car doesn't work and these pizzas are
getting cold!"

The mechanic came and towed the car back and immediately discovered
that the engine had no oil.  Suspecting the worst, he looked to
see if the engine has been damaged beyond repair.  It had.  He
installed a new engine, this one with electronic ignition.  He
didn't notice that the battery was hooked up backwards, though, so
the electronic ignition module blew up when he tried to start the
car.

Meanwhile, the pizza man was calling every half hour wondering if
his car was ready.

The mechanic was now *really* *irritated*, and he had to spend a
good long time checking out the car for anything else that might
be wrong.  What else did the pizza man do?  bleed out all the brake
fluid? put too much air in the tires?  Who knows?  The pizza man
swore he "didn't change anything".

Eventually, the mechanic got the car working and sent the pizza
man on his way.  2 weeks later, the pizza man was back, this time
with transmission problems because he poured motor oil into the
transmission fluid.  The mechanic never even thought to look for
that...

Meanwhile, the boss starts bitching out the mechanic because 1)
"You're spending way too much time on the pizza man's car!", and 2)
"Why don't you have it working yet!?!?  He has pizzas to deliver!"

Nobody lived happily ever after.