Rattle just noticed at start up + drive.

Which engine do you have? Can you hear the noise inside?

A very common problem is a rattling AC compressor clutch bearing. They can sound like the engine is coming apart. The best way to identify that is by removing the serpentine belt, then feeling the pulley while you spin it by hand. You might also see the outer plate of the clutch trying to turn with the engine running and the AC / defroster off.

'96 and newer models should be giving you three-digit codes in the odometer display. How are you getting a two-digit code?

Injector clicking is normal. You can hear them without a stethoscope. For the record, Chrysler has extremely little trouble with their injectors over the entire life of the vehicle.

It sounds like you might be describing the purge control solenoid. As I recall, it sits somewhere behind the right head light. When the Engine Computer decides the time is right, it cycles that valve on and off about twice per second, and it is rather loud. They can often be heard from inside the van so people have been known to wrap them in foam. You would recognize that as a very steady thumping or clicking. The compressor clutch will be an uneven rattle or clinking sound, and it will not occur when you run the engine with the serpentine belt removed.

You're better off running the oil low than using 80 weight gear lube. That will do the job of isolating moving metal parts from each other, like engine bearings, but there are no detergents, anti-foaming agents, seal conditioners, or other additives in it. I haven't pulled the drain plug on my '88 Grand Caravan daily driver in over nine years! I replace the oil filter about once every three years, and add a quart of 10W-40 when the lash adjusters start making noise. In 3,000 miles, I add about two to three quarts oil. Each one replenishes the additives. Obviously that is abuse, not just neglect, and I'm not suggesting you do the same, but with 381,000 miles and only one timing belt / water pump repair, it shows what some of these engines are capable of. My 3.0L is nothing special, reputation-wise. Your 3.3L has a very good reputation as a strong engine. I've already run my oil so low that it took a quart just to get a taste on the dipstick. That means it was 3 quarts low. A full oil change only takes 4.5 quarts. I'm only sharing this sad story to put your oil level concern in perspective.

As a further point of interest, all engines use some oil between oil changes, and to reduce the number of complaints, all oil dipsticks are now marked with "min." And "max.". They no longer use "add" and "full". The oil level IS going to go down as you drive, but as long as it is anywhere between the two marks, it's okay. If the level starts out on the low end right after an oil change, nothing will happen if it goes a little below the "min." Mark.