Genuine GM Fluid 88861803 X66P Upper Engine and Fuel Injector Cleaner. This is a new old stock bottle of AcDelco Fuel Injector/Upper Engine Cleaner commonly used on LB7 LLY and LMM Duramax engines. No longer available from GM. Factory sealed bottle as shown in pic. You must be familiar with the proper use of this Fluid as per the GM TSB.