Engine Oil Grade change, Toyota 4E-FE in Corolla XE G 2000

[alpha230194]

We've recently bought a Toyota XE 2000 with 1331cc 4E-FE engine (changed in 2018) in it.
I don't know exactly how much KMs is this engine driven, but it is definitely below 100K in this car at-least. (I'm also not sure if they bought a new engine or used, but the purchasing price was 63K in 2018). So the previous owner was using Shell 20w 50 engine oil in it and asked me to keep using the same.
I've seen many people saying that this Grade is not ideal for any car. So the question is, can I change the grade of this oil ? What are the risks involved? Which grade or brand should I use ?

Currently the engine is giving around 10KpL in city with AC. Sound is minimal and there's no smoke whatsoever.
Thanks in advance.

[399.ak]

Recommended oil is 5w30, 10w30 and 10w40.

Use any good shell, PSO, zic, total, aisin.
It doesn't matter how much it's driven. Using recommended oil is always better. 10w40 is better choice. The worst you can face is a bit oil consumption and little smoke.

[alpha230194]

Recommended oil is 5w30, 10w30 and 10w40.

Use any good shell, PSO, zic, total, aisin.
It doesn't matter how much it's driven. Using recommended oil is always better. 10w40 is better choice. The worst you can face is a bit oil consumption and little smoke.

@399.ak Will that smoke be permanent? Will it reduce or increase with time ? Any effect on engine noise?
Please suggest. I really don't want it to be messed up

[399.ak]

Depends on the condition of engine.
If valve seals are in bad condition so there will be light smoke. If rings are worn out smoke will increase.
Better get compression test it will tell about engine health.