Lots of oil seals on a 306 need to know which one
probably 10W40
use the dipstick
5w40
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
4 quarts
Under the engine, towards the back of the sump.
with filter 3,7 without filter 3,2
on the side of gearbox at top a remove ns wheel to see it its an 8mm hexagen shaped bolt
I suggest you open the bonnet and look at the front of the engine below the exhaust manifold, it's very easy to see.
Several things could cause an oil leak in a 206 Peugeot including a bad cylinder head or a problem with a pulley oil seal. There could also be an issue with the rocker cover gasket.
sounds like the head gasket has gone.. Has it got a oil cooler if so that can leak oil into the water.It is located on the front of the engine and is easy to replace.The biggest job is cleaning the oil out of the water