Joe,

The capacity of the engine may be 8 liters but that is with a dry engine. If you didn't get all the oil out of the engine, adding 8 liters may make it overfull.

Did you drain the oil cooler and oil lines? If not, you didn't get all the oil out of the engine.

If there is too much oil in the engine, the crankshaft can beat the oil into a froth and air can get sucked in (actually pushed in by atmospheric pressure) by/to the oil pump and might cause damage to the bearings.

Go by your dipstick. If it shows overfull, drain some oil out.

P E H