...just supporting what Sven said, I've done a dozen+ coolant drains/fills on the 240's and never had a "burping" problem. Thermostat bleed hole/jiggle pin at 12:00, fill the reservoir tank to the 'Max' line, wait a few minutes and top up if nec., then start and fully warm up the engine. Watch the temp gauge and look for leaks to make sure all is well. Shut down overnight and check the reservoir in the AM - at most, I've had to add 4-500ml. Check also for any signs of overnight leakage under the car, and in the belly pan.

If I've changed out to fresh coolant and I'm expecting cold weather soon, I'll use the block drain to lower the reservoir level to the very bottom, then pour what came out of the block back into the reservoir. Yeah, overkill, but this makes sure the pure water that is typically used to top up the reservoir is now mixed in with Glycol, and the whole system is reasonably consistent in Glycol concentration and won't freeze. This would happen anyway through a number of heating/cooldown cycles, but if it gets below Zero before that, you could have a problem.
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Bob (son's 81-244GL B21F/M46, dtr's 83-244DL B23F/M46, my 94-944 B230FD and 89 745 (LT-1 V8); hobbycar 77 MGB, and a few old motorcycles)