86560sel,

Not to tread on any one's toes here,BUT I wouldn't over stress an engine with
an "Italian Tune up" until I knew it was in the mechanical and maintenance
State of Tune to Safely "Blow It Out"

ALWAYS better to replace Old Unknown fuel with fresh Diesel...AND two years
is a LONG time with no Stabilizers (or Enzyme additives to keep the Algae at bay)
...BUT the Startron will break down any microbial infestation, allowing it
to pass through the filters without clogging them(or bothering the fuel system).
AND the Redline will help bring the Cetane and other Diesel components up.

I've got Diesel sitting in a container that I added Startron to 2 years ago...
total storage time ,However is 4 years...Won't that be interesting to look at
in 5 or 6 months?

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'84 300SD sold
124.128