Too loose will clatter and beat parts up like funrunner said. Your valves won't open to the lift they should so you get a power loss. I don't know if the knock sensor would pick that noise up.
Too tight won't allow your valves to close all the way so exhaust valves can burn, intakes can allow compression loss, and like funrunner said if tight enough, contact with piston.
If you don't hear ANY ticking, your valves are probably too tight. It will run rough. My son adjusted his valves and told me it wouldn't idle very smooth. It ran but was shaky to say the least. Some of the valves were ok but most of them were way tight. Luckily he didn't run it very long.
Since some of the valves were set ok, you could hear the ticking. So he didn't think there was a problem. It ran like crap though. Definitely a power loss.
Like I posted before I set mine at .007 and .011 with no problems. For your peace of mind, set them to spec and get used to what is normal mechanical cam noise.
If it gets quiet over time you better check em.
I have never noticed a change in how loud with different oils like you have. I have used different brands on occasion but always used the same viscosity.
Getting back to your original post, ticking is normal. Maybe compare to some other Toy's.
