Others may say differently but I have been doing oil changes on my 560 w/290k miles the last 13 years the "normal" way that other cars are done the same where you dump the oil, install new oil filter and oil then you should be good to go.
When checking for the chain guides, also check the chain to see how much it has stretched. It's a good car to keep if you can do most of the work yourself.
just enjoy the car and sleep well.
