Hi everyone, i'm brand new to aw11 ownership (having only owned a honda civic before) and I have a couple of questions. 
 
1) where should my oil pressure gauge be reading during normal driving. Right now it sits at about 1 peg above the centre.
 
2) What is the door lock button on the inside of the driver door meant to do? currently mine will unlock the passenger side door, but it does not lock either of the doors when pushed the other direction. its odd because the inside of the door locks move as though they are being locked, but when opened from the outside they remain unlocked.
 
thanks for any help!

oil pressure sounds fine, the gauge isn't super accurate and sitting over half is fine while driving, some sit lower some higher.  
 
door lock button is like an emergency lock to lock both doors while inside or can be used to lock both doors before holding handle and closing drivers door on exiting the car.  the linkages can get stiff or may have fallen off at the lock, you'd need to remove door card and have a look at whats going on.   both doors should lock when using the key from outside on either pass or drivers door. 

Yep above comment has nailed it. The standard gauges really aren't the greatest sadly but it doesn't sound like the position of yours is cause for alarm. 
 
Yep over time the electrical contacts and grease in the lock mechanisms fail and will need cleaning. If you take the door card off and just have a look how its meant to operate you should be able to see the parts that are causing it not to work. I'd reccomend buying a can of electrical contact cleaner and spraying that in the plugs that are causing the issue as well for good measure.

thanks for the info guys, i havent yet pulled apart the door card, but just some extra info. when i use the lock switch on the drivers side door it attempts to lock the passenger door (and it does unlock the passenger door), but apparently it doesn't actually fully lock.
 
also a tertiary question. my gear shifter is reasonably loose (no real trouble getting into gears, just has a bit of side to side play in the slots). is this an issue with the bushings and if so would you guys recommend the brass ones you can get from twosrus?
 
thanks for all the help!

Until you pull the door cards off and give everything a once over you won't solve the issue.  Be sure to squirt some wd40 or penetrative lube of choice into the key hole assembly too. 
 
The brass bush on the gearbox linkages can usually be turned around and it only wears one way.  Some people have had good luck with skateboard bearings, which is what i'll probably try/use next.   In 23 years never seen wear from the shifter assembly in the cabin.  
If you're pulling that apart to look or clean and re-grease it isn't too hard to make your own short shift kit while you're at it. 
 
 
 
 

Lost play shift issues are usually at the gearbox cables end. They are rubber buffered and 30 yrs is plenty for the originals to just break in the same way you might see on a figure 8 engine mount. Skate board or solid bronze will add unnecessary twisting loads to the cable. A GEBK8S spherical bush fits just as easily, will feel similar to the bearing or solid bush and wont load up the cable. Around 3-10$ in Bronze on chromed steel.

2lateforPplate
Lost play shift issues are usually at the gearbox cables end. They are rubber buffered and 30 yrs is plenty for the originals to just break in the same way you might see on a figure 8 engine mount. Skate board or solid bronze will add unnecessary twisting loads to the cable. A GEBK8S spherical bush fits just as easily, will feel similar to the bearing or solid bush and wont load up the cable. Around 3-10$ in Bronze on chromed steel.

Good advice