Later Minis used silicone brake fluid, in the brake and clutch masters.
To determine if your car has silicone brake fluid; the colour of the  fluid will be purple or green but not clear or black.... old brake fluid turns black from the contaminants. If it is black it is time to flush it.
Engine oil: We use 15W50 Mobil One and add 2 ounces of Red Line engine break in additive .
There are special oils made for old engines that require Zinc.
Some people in our club use Harley Davidson oil. Expensive...
Minis need 5 quarts of oil if they do not run an oil cooler and 6 quarts if they run a cooler.
The engine and transmission share the same oil.
1992 Should run on lead free gas but if not then you will have to add a lead additive at every fill up.
The higher the octane the better 91 or 94.
If the engine is high compression and the octane is not high enough it will run on when you shut the key off.
If it has a carb then you  have to fill the carb piston with oil too.
Buy the Haynes Manual and read all about your Mini.
Also when changing the oil be sure to grease the rear radius arms.
Debbie

Yes the same oil. 
In Florida i use 20 W 50 but some owners prefer 10 W 40.
The problem i have found with the automatics is most owners have not maintained them as they should have and usually get sold with dirty oil. This and heat is the biggest issue with automatic Mini's. 
Your first oil change imo should be done with a cheaper throw away oil after maybe 100 to 200 miles to clean it out and know exactly what you are working with
They are good units if serviced correctly. I have a friend with one and he changes the oil every 2000 miles and the filter every 4000 miles and it gets driven pretty much daily and for long 500 miles plus journeys with no issues.
The automatics only have basic 60's mechanical adjustments. The bands can be adjusted once you bend a wrench to get to them along with the govenor/kick down rod.

Gecz28, Welcome to Minis. Read your workshop manual (probably by Haynes) and take a good look at the engine and gearbox (transmission). The gearbox acts as oil storage for both the engine and gearbox.
And pay attention to malsal's posting for fluids to use.

So use the same motor oil for trans? 
I live in pittsburgh. It will just be a nice weather car, no winters. Summer temps around 90*

I like that "if in doubt, flat out".

Depending where you live and how hot it gets either 10W 40 or 20W 50 for the auto trans, mineral oils only no synthetics. Also look for oils with enough zddp in it.
You need to change the oil every 2k miles in auto's.
Anti freeze just use the regular green stuff again depends on your location on the strength you use, the least you can get away with the better in the small capacity Mini cooling system.
Brake fluid DOT 3 or higher, if you are just adding it probably has DOT 3 in it.
Power steering fluid, Mini's were never produced with P.S.

yea.. I left out the W...

Bill there is 10W40 and 20W50

DOT 4 for sure..  I use 50/50 anti freeze.. I also use straight 40 W in all my minis.. but most folks use 10W/50..  later bc..corrected..  

Hey guys. Newb question, im still waiting on my mini. What fluids would you recommend? Oil, trans, antifreeze, brake and ps fluid?