Classic/Antique Car Repair: 3 on the tree, pontiac laurentian, rd gear


Question
Roger
It is a 230 straight 6.three speed on the steering column.
Just to confirm,I should be driving(city) mostly in second?
Also,what type of oil should I use? Should I use an additive? What about oil filter?
I noticed a bit of oil on the engine block that must have blew out of the cap.I have been told that this is not unusual,and I should wipe this off regularly or put a rag around the cap.What do you think?
Also,is regulsr gas OK? Thanks so much.-------------------------
Followup To
Question -
Hi Roger,Happy Easter
I was looking through the original manual that came with my 64 Pontiac Laurentian.
Mine is a three speed three in the tree,but a four speed floor shift and an automatic were also available,with different size engines.
Why the differences? Is my car,with the smallest engine and least gears meant to be used for sedate driving,as opposed to the four speed big engine for highway trips?
Also,what gear should I be driving in in the city? I have the tendency to shift all the way to third,but when I slow down it 'lugs'-shoud I drive in second and save third for the highway?
Thanks!
Answer -
Barry, Happy Easter to you also;
 Well as far as your tranny , you do not have a clutch- right .the 3 rd. or 4 th gear would be for hwy. or  35+ 40 mph.  and the lower gears for in town and on hills, or loads etc.I do not know what engine you have a 6 or v8 ?
and as with any car/truck , etc. the lower gears are used for short distances / take off and / or hills  and the end gears for  hwy. use.  as far as your 3 rd gear driving in town I would use 2 nd. and shift to 3 rd when needed.  
so use the 3 rd for hwy. use  because the drag on the engine will only cause you a loss of power and pep so use the gears that you feel right with as long as the car runs right for you than you will know what gear to be in  ok.  

Answer
Barry;
   As far as the gears you can use the gear that you need, and if 3rd is to sluggish in town than use 2 nd.  and you only have a six cyld. so 3rd gear should be used when you are  on a main drag or if 2nd gear starts to wind out than shift. Oil is no big deal  use a good 10-w-30  or 10-w 40
and a can of STP oil treatment no other kind and do not use  any other addatives as they are all  junk, only  STP. is good.and as far  as a gas addative  a can of dry gas is ok with a tank of gas (regular) is all you need in that 6 cyld. hi test gas would be a big  waste of money  and  the oil  filter  any brand name is fine for it  ok.  good  luck.