LT = dry clutch (or at least pray it stays dry
You will get 20 answers from 10 members on oil.
My .02 cents is that I have never seen an OIL related failure on any vehicle besides running low or out of oil..
Here are most of the important data from the Manual
Tire I use
ME880 120/70VB17 Front
METZELER ME880 120/70VB-17 FRONT K1200LT (110-10447)
ME880 - 160/70VB17
METZELER ME880 160/70VB-17 REAR K1200LT (110-10448)
Oil = Brand-name HD oil, API classification SF, SG or SH; suffix letters CD or CE are permitted; alternatively, brand-name HD oil of CCMC classification G4 or G5; suffix PD2 is permitted.
GearBox Oil .75 to 1 QT
Brand-name SAE 90 hypoid gear oil, API Class GL 5
Rear Wheel Oil / final drive .25 QT
Brand-name hypoid gear oil, SAE 90, API class GL 5.
Coolant - 2.6 US quarts
Antifreeze Use only nitrite-free long-term antifreeze and corrosion inhibitor.
For the quantities, check out the service manual in the HOW (Hall of Wisom)