Yep the idtec is a different engine entirely and has a different torque profile and characteristic. A decent stage 1 really unleashes their potential though.
C3 has some fairly abrasive additives that are used to help break down the ash dilution from the dpf, that’s what gives it the ‘low saps’ rating. An older (and ironically often cheaper) C2 without these abrasives are better for your engine in my opinion. But the key is it’s only better if the...
Brand isn’t important in my opinion, viscosity and ratings are. Fundamentally if your dpf is still present then stick to a C3 low saps 0w30 and if it isn’t then I would recommend a 0w30 C2 instead.
Investigate what’s causing the high emissions output and solve it. The car is likely over fuelling, could be down a number of things including a bad egr, bad injectors or a boost leak.
If you can’t see the reset service indicator option it means your maintenance minder has been disabled (either at PDI or later by someone with a HDS). Once disabled, it can’t be re-enabled as far as I’m aware.
If it’s something that has developed suddenly then that’s something different. Might be something as simple as tyre pressures, try running a higher psi. It may even be a failing tyre compound.
If you’re on 17s and above then this is sadly a trait of the 7th gen Accord. Try temporarily switching to 16s and see if it eliminates it. Ensure you stick to correct rolling radius. 17s should be on 225/45/17