Whats the best oil for lets say a 2021 toyota corolla? Is it always the one recommended in the owners manual?
Name brand(s) proper weight for your driving condition and SN+. That's the best available and is great oil. Cheapest is usually Pennzoil in my area.
When in doubt, use what is in your manual.
Sometimes things change though, and other oil weights can be recommended by the manufacturer.
How do you check that updated information?
I would call Toyota and ask.
Consult owners manual for SAE rating (viscosity...commonly called weight, ie: 5w20).
Go with what the manufacturer recommends as to using conventional, synthetic, semi-synthetic.
Also for the recommended, at the time of manufacture, API rating (ie: SN)...as newer oils are approved the second letter follows the alphabet..."SO" is being skipped, next is SP...the newest is an upgrade to the previous. Exception would be high performance/exotic and vintage/antique engines.
Gasoline..."spark" engines require "S_" oil.
Diesel...."compression" engines require "C_" oil.
Every oil container is clearly marked as to SAE and API ratings.
