These are my findings after 3 years of ownership.
Do a Vacuum test. It is simple and reliable enough to pin point deficiencies.
Most workshops here don't do it. They like to guess-ti-mate. Owner keep spending...
If you own an older car, tune the intake and exhaust valve lash (clearance).
Again, the vacuum test can verify the correctness of the valve tuning.
Worn / Out of alignment valve tune can result in sluggish power & use more fuel per run.
Change oxygen and air sensors.
It is part of wear and tear component. Life span about 100k km, same as spark plug.
These sensor are part the combustion computation feedback vs air & fuel for e-throttling.
Clean MAF and renew air filters together during regular 10k or half yearly Oil Change Interval (OCI)
Maintain good tire pressure. Preferred 35-36PSI.
Non critical replacements
Spark plug type not critical.
Engine oil brand not critical. Viscosity maintain at least 30. Or 40 for older engines.
ATF oil change needed if the magnetic sump plug attracts A LOT of metal or color is not bright red.
Either way, seeing a lot of metal deposit means transmission is in trouble!!
Throttle (butterfly valve) no need to clean.
Don't ever flush the oil system.
Most importantly, as an experienced mechanic once told me....
Change each variable ONE at a TIME.
So when problem surfaces, you can identify and fix it.
As you can see, most mechanics don't like what i say cos they make minimum out from me.
Enjoy your drive!
Here are some useful tips/url for self maintenance owner
Metric spanner & 3/8" drive box spanner, Allen wrench - Get from Daiso. Cheap!
Honda Workshop Manuals
Tip: Select the similar year & engine type from the Honda Civic list
Part Number Tracing