[ctrlz]

Originally Posted by easttxss

You should be fine to just run it and top off.

Do not drain the fuel.
Your original plan to drop it to 3/4, then refill is fine. easttxxss is right, but your plan will probably make you feel better, and certainly won't hurt!

[XinLiu]

Originally Posted by ctrlz

Do not drain the fuel.
Your original plan to drop it to 3/4, then refill is fine. easttxxss is right, but your plan will probably make you feel better, and certainly won't hurt!

Thanks easttxss and ctrlz.

I feel much better now. I will drive the car and use up 1/4 of the fuel and then add fuel to full!

[LT4Greg]

No the fuel treatment wouldn’t be the cause of the problem you are experiencing. I’m thinking either battery or your temperature sensor is on the way out.

[XinLiu]

Updates:

I installed a brand new battery.
After a week the problem come back again.

Fan maximum when engine starts, fan persists for ~10 mins when engine turned off.

OBD2 reads:
P0128
Coolant thermostat - coolant temperature below thermostat regulating temperature

The current plan is to replace both the thermostat housing (katech 174 thermostat backordered and GM only sells the thermostat housing) and the coolnant sensor

Though I do still see the coolnant gauge working properly after disconnect and reconnect the negative terminal of the battery. I plan to replace it since cheap.

Some people fixed the issue by playing with the wiring and relay in fuse box (their wiring seems to be loose or something). But I think they are either lucky or does not solve the problem permanently.

But this makes me wondering whether a low battery can mess up with the relay or wiring. I don't think it could.

Any comments and suggestions are welcome.

[JoeTX]

take it to GM and let them check out the car or your mechanic they should be able to tell you what the issue is.
as others mentioned it might be thermostat and temperature sensor issues.