B767-300 Captain reported numerous systems failures after receiving the aircraft from an A check. After departing with the Right IDG deferred and a pack deferred on an ETOPS flight; the flight crew received an APU Oil Level Low Status Message. The flight crew elected to divert and make a precautionary landing due to the risk of a single generator operation during ETOPS.

Narrative

We picked this airplane up in ZZZ for a planned five leg trip over three days back to ZZZ1 . The airplane was just out of a maintenance A letter check. The airplane was allowed to leave the maintenance facility with outstanding maintenance issues. First day; Date; three legs ZZZ-ZZZ2; ZZZ2-ZZZ3; ZZZ3-ZZZ4. Auto Cabin Pressure Controller was deferred. By the time we landed in ZZZ4 we had disconnected the RH Gen/IDG and had Stab Trim EICAS messages. On the Date1 we departed ZZZ4 for ZZZ5 with the RH Gen deferred and the Pressure Controller. On the ILS approach to ZZZ5 we had GS/AFDS; Autopilot issues which resulted in two missed approaches. A separate [report] was filled on that event. At block-in at ZZZ5 we wrote up the second Pressure Controller; the Stab Trim EICAS; the GS/AFDS Autopilot malfunctions. While in the blocks in ZZZ5 the L Pack tripped to do overheating. The next leg ZZZ5-ZZZ1 was a planned 120 minute ETOPS rather than the 180 due to the RE Gen deferral. Now that the L Pack trip could not be reset we were restricted to 60 minutes for the crossing. The GS/AFDS write up resulted in the R-FCC being deferred. MEL items prior to ZZZ5-ZZZ1 leg we had: L Pack; #2 Auto Controller; RE Gen/IDG; R-FCC ( Right Auto Pilot). The planned 8+15 hour flight took us over [Region1]; South of [Region2] and over the Southern tip of [Region3] and into northern [Region4]. Approximate position XXXXN we got a APU Oil Low Status Message. The APU is our backup to the RE Gen being deferred. I made the decision to divert. Dispatch was contacted and a suitable airport was selected and agreed upon; ZZZ6. After block-in the Stab Trim was again written up and the Fuel totalizer/Calibrated system. We had a 4;600 lbs. discrepancy with 60;000 lbs. of fuel onboard. (This same fuel issue was written up by me in Date2 after landing in ZZZ6 IFCR on the divert. R/H Generator/IDG had been disconnected en-route on the previous day's flight do to an EICAS message; Date1; ZZZ3-ZZZ4. The APU was started before the disconnect. The MEL was added on the following day flight to extend the DDG 3 day limit before repairs had to be made. Two legs were planned to be flown on the Date3 ZZZ4-ZZZ5; ZZZ5-ZZZ1. The APU was required to operate the entire time to provide generator power for the deferred RE engine generator. At approximately position XXXXN a Status Message revealed APU Oil Level Low. Losing the APU because of a auto shutdown event would create a single source of electrical power and an in-flight situation. Dispatch was contacted via Sat-phone and a suitable diversion airport was agreed upon. It was estimated the APU had been running between 18-22 hours continuously before shutting it down in ZZZ6. Maintenance confirmed there was a leak.Taking an airplane out of a maintenance facility with outstanding and long running maintenance issues. You have Mechanics that live on these planes day in and day out and are in the best position to address maintenance on the specific airplanes when in for a letter checks. There is no excuse. The MEL/DDG system is designed to get a plane back to base where repairs can be made. Not to carry maintenance items till a plane breaks hard. These situations are tough on the flight crews and cabin crews as well. It make our days longer; 22 hours in this case. Days-off and crew members personal lives are affected. Having my name associated with flight cancellations and diversions because of prior decisions beyond my control is not desirable.