I am not eh expert to say, but I believe the tick, tick is normal for initial starts since the oil is on the bottom or the pan. The oil did not have to be drained on mine, so I doubt it will need to be drained on yours, you can change the filter with out draining the oils since the filter housing sits higher than the pan and not on the bottom of it like most cars. The fact that you did not fried the engine or lost power tells you that your pressure is actually/probably good it is the sender or the gage. So in other words the delivery of what is actually the pressure is what you seem to have at fault here. I am not sure about that commercial and I am not daring enough to try that with my baby. I run synthetic in mine.

__________________
1993 400SEL (W140) 281K
1999 S500 (W140) 163K (Sold)
2002 S500 (W220) 72K
1999 S500 (W140) 88K
You cannot simultaneously prevent and prepare for war.
Albert Einstein (1879 - 1955)