I suggest you open the bonnet and look at the front of the engine below the exhaust manifold, it's very easy to see.
with filter 3,7 without filter 3,2
Lots of oil seals on a 306 need to know which one
probably 10W40
use the dipstick
5w40
After the air filter and on the intake manifold
how to remove hex nut when changing oil filter on peugeot 207
10w40 is fine
The gearbox oil fill plug can be located, in your Peugeot 306 2.0, on the top of the gearbox nears the back. The plug can be removed with a three-quarter inch socket
I think its under the rear seat
peugeot 308 hdi
4 quarts