Hump-day Maintenance!

Yesterday was oil-change and maintenance day for my Magna. 244,000km (or 151,000 miles) which saw throttle and inlet mainfold clean treatment, engine oil flush, new oil and oil additive, oil filter, air filter, and fuel treatment.
Makes me wonder, how many Oppos do their own maintenance on their cars? I bet the majority of us do - maybe because its cheaper or maybe you, like myself, just enjoy doing it.

What kind of maintenance do you do?
What do you leave to the professionals?
What items or techniques do you swear by?

Hump-day Maintenance!