Adding a small amount of oil to the cylinders raised the compression appreciably? As v8volvo stated earlier, that can point to piston ring sealing issues.
Now come the questions:
Is there an actual problem with the ring sealing? Did the engine sit a long time inop? Sometimes that can cause the oil normally present around the rings to dry out. But you say it ran poorly in your test? They should easily have relubed and sealed up by then.
What is your compression testing method? Adaptors? Engine cranking speed?
Did they all consistently raise compression by the same amount?
Your measured 29 bar (421 PSI) is quite good! Close to factory spec new (455 PSI), well above min. (313 PSI).
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1985 744 gle d24t
1985 745 gle d24t
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