There is no need to do top overhaul, for now.

If your exhaust is blueish in colour (which is quite hard to determine, even by experienced car drivers or some mechanics) then the engine is not leaking engine oil , but is consuming engine oil.

Next is to check/determine whether engine oil consumption problem is caused by:
a) hardened (exhaust) valve seals and/or
b) clogged piston rings.
In either case, there is remedies in a 10 year old Toyota engine.

This post has been edited by zeng: Aug 16 2022, 01:54 PM

I'd been changing engine oil between 16-21k km (fully synthetic) intervals for like 5-7 years in a 2007 toyota odo 340k km.

Before that was 7-12k km for semi-synthetic and 6-9k km with minerals like 15W40 or 20W50 since around 2010.

Till todate I have no engine oil consumption problem.

However I do have engine oil leaking problems like valve cover gasket leaks (rectified) and at the moment, front oil seal/timing cover leaks of about 200mL over 12k km usage which remains unrectified (Note: no dripping drops on overnight parking).

Have a read on 'Italian Tune Up' for stucked/clogged piston ring related oil consumption problem.

Using federal highway to work at KL Sentral and returning to Subang Jaya thru NPE, plus S Jaya internal roads etc.

22-24k km per year before covid, 18-19k km per year during covid 2020 2021...

Fully synthetic Shell Ultra 5W40 and currently Mobil 0W40.

Semi was Total Quartz 7000 Energy 10W40.

Mineral was Shell/Petronas 15W40 and 20W50.

Post #1 Blotter Spot Test

bobistheoilguy


Edit:
No Used Oil Analysis was ever done though. However as almost all Toyotas factory recommended oil change intervals in US is 10k miles (16k km), its UOA's returned very low wear count particles at 10-15 ppm of metals (consisting of iron, aluminium, copper, nickel, zinc, chromium and lead), way way below 'caution' levels let alone 'critical' levels adopted by most laboritories in US or Russia.

This post has been edited by zeng: Aug 18 2022, 10:40 AM