Let me know if i shouldn't start a new thread,

My Corolla 2003 coolant level drops slowly when not driving. Already had mechanic checked, they put some sort of pressure pump thing to test, but no leaks observed. changed the radiator cap but still dropping.

The behavior is very weird, when driving everyday, it doesn't drop at all, even driving from jb to kl it doesnt drop anything. But when I park my car there for 2 or more days, it starts to drop. Sometimes my friend fetch me during weekend(Sat & sun) for like 3 weeks (total 6 days over 3 weeks) then it drops below the 'LOW' level.

Some says it's engine consuming the coolant, but it doesn't explain driving from jb to kl doesn't drop any level. It's really annoying as it only drop sometimes when not driving.

Any sifus can help? Thanks.

I just bought original long life coolant and really keen to put it in asap but it's leaking now.