Mahal lo if only labor

As I understand it, there is no catalytic converter. There is
no mention of it in the owner & service manuals.

The Haynes manual mentions it only in the EFI version of
the Iswara (see below) and the exhaust pipe is in 3 parts.
There is no part in the LMST exhaust resembling the catalytic
converter in the photo.

Oops I missed that one - it was mentioned in 2 places
like it was copy & pasted.

The warning that low fuel can  damage catalytic converters
is strange.

Normally it is understood that lead, oil, coolant or unburnt fuel
will damage the catalytic converter. I wonder how low fuel level
will cause it. (For  fuel-injected engines the fuel pump inside the
fuel tank will be damaged if the level is low because the petrol
cools & lubricates the motor. ) 

Anyway I compare photos of the underside of an LMST with the
Haynes manual photo and I find there is none at the location.
The center box do not look like a typical catalytic converter.
Maybe other members here can shed some light on this matter.

it's suitable to use this on saga ? I rmb that it's stated 2ow50 on my 4g15p sticker .

isnt that is too thin for saga ?

1) How steep was the slope? Use 1st or 2nd gear, and for how long?

2) Did the needle go to the red zone? or only slightly above normal?

3) How is the condition of the coolant in the radiator? Any air pockets,
corrosion, deposits in the water tubes?

From your reply, the gauge would be showing the temperature
position like in the photo, together with Proton manual instruction
for this issue. That would mean the engine is not overheating.

However, the concern is there is a change from your previous
experience. The reason could be different conditions (steeper road,
hotter day, heavier car loading, more wheel/tyre/road resistance ... ),
or, a deterioration in cooling performance.

When you changed your coolant recently, did you see rust, dirt,
teh-tarik colour coolant  etc when the cap was opened and old
coolant drained out? If there was, and if no flushing was done
there could be some rust coating the tubes or passages and this
reduces heat removal.

If there is a sudden leak at the overflow hose or cap, air pockets
can form by drawing in air instead of coolant when cooling down.
You can check this by opening the cap in the morning before you
start the engine.

Also look at the condition of the tubes visible when
you open the cap, to see if there are scale or coating
the insides.

The horn fuse is in the fuse box (No.13) but the
headlamp fuse is inside a capsule attached to
a wiring harness near the battery. You could check
both to confirm.

The circuits for horn and headlamps are separate, and
the only things in common are possibly only the supply
at the steering column, and the earth near the bumper bracket,
but I am not sure as I do not have the wiring harness diagram.