Back in 6-2-2011, Char Baby was nice enough to start this list. I copied it and kept it updated with every acronym used on BITOG since then.

If the group would proof read for errors and list any I might have missed, I this this would make a good sticky.

AAP=Advance Auto Parts
ADBV=Anti Drain Back Valve
API=American Petroleum Institute
API-TC=2 cycle, air cooled engine oil specification
AZ=Auto Zone
BITOG=Bob Is The Oil Guy
BOGO=Buy One Get One Free
BP=British Petroleum
COF=Coefficient Of Friction
CP=Conoco Philips (makers of MotorCraft/Kendall/Philips66 and others)
CRD=Common Rail Diesel
Dino=Regular Motor Oil(s)
FAR= Free After Rebate
FF=First Fill
FLAPS=Favorite Local Auto Parts Store
FS=Formula Shell
Fuchs=European MFG of quality lubricants
GC=German Castrol...Castrol Syntec, It will say "Made in Germany" on the back. New name, changed to Castrol Edge
HDEO=Heavy Duty Engine Oil
HDMO=Heavy Duty Motor Oil
HM/HMO=High Mileage/High Mileage Oils
HTHS=High Temperature, High Shear rate viscosity
IDR=I Don't Recall
IIRC=If I Recall/Remember Correctly
ISO=European Standards
J300=SAE engine oil viscosity classification standard
JASCO=Japanese Standards
KV=Kinematic viscosity
LOS=Lucas Oil Supplement
M1 AFE=Advanced Fuel Economy
M1 EP=Extended Performance
M1 ESP=Emission System Protection full synthetic deisel oil
M1=Mobil 1, all Mobil 1 oils are full synthetic
M5K=Mobile 5000 mile Dino oil, discontinued
MC=MotorCraft...Not Mobil Clean
MM=Maintenance Minder
MMO=Marvel Mystery Oil
MOA=Motor Oil Additive
MOFT=Minimum Oil Film Thickness
MOS2=Molybdenum Disulphide
NMMATCW3=National Marine Manufacturers Association
OBD=On-Board Diagnostics/engine codes
OCD=Obsessive Compulsive Disorder
OCI=Oil Change Interval
OCOD=Orange Can of Death
OD=Over Dose
OEM=Original Equipment Manufacturer
OLM=Oil Life Monitor
OP= Original Poster
OP=Oil Pressure
OPE=Outdoor Power Equipment
OT=Oil Temperature
OUO=Oil of Unknown Origin
PCMO Passenger Car Motor Oil
PO=Previous Owner
PP=Pennzoil Platinum
PU=Pennzoil Ultra
PYB=Pennzoil Yellow Bottle
QSDefy=Quaker State Defy
QSED=Quaker State Extended Durability
QSGB=Quaker State Green Bottle
QSUD=Quaker State Ultimate Durability
RL=Red Line oil
SBC=Small Block Chevy
SLOB=Street Legal Octane Booster
SOPUS which stands for Shell Oil Products United States
ST/STD= SuperTech/SuperTech Dino
STS=Super Tech Synthetic
TC=Spec for low ash 2 cycle air cooled engine oil
TCW3=Spec for no ash 2 cycle liquid cooled engine oil, W means Water cooled
UCL=Upper Cylinder Lubricant from Lucas, a gasoline additive
UOA=Used Oil Analysis
VDB=Valvoline DuraBlend
VI=Viscosity Index
VML/ML=Valvoline MaxLife/MaxLife
VOA=Virgin Oil Analysis
VSET=Valvoline Synpower Professional Engine Treatment
VSOT=Valvoline synpower oil treament 15 oz VSOT (Valvoline Synthetic Oil Treatment)
VWB=Valvoline White Bottle
WPP=Warren Petroleum Products
XOM=Exxon Mobil
YMMV=Your Milage May Vary