If there is oil in the radiator top up bottle the most likely cause is that your head gasket has blown and the oil is leaking back into the cooling system. A couple of checks you can do is 1. remove the oil filler cap and look inside the top of the engine and look at the filler cap if there is a grey residue (emulsified oil) then your head gasket has most likely blown also you can remove the radiator filler cap and start the engine, if there are any bubbles coming up in the radiator bottle this is also a pretty sure sign that hte haed gasket has blown. Not a cheap job to repair. Hope this helps. If there is oil in the radiator top up bottle the most likely cause is that your head gasket has blown and the oil is leaking back into the cooling system. A couple of checks you can do is 1. remove the oil filler cap and look inside the top of the engine and look at the filler cap if there is a grey residue (emulsified oil) then your head gasket has most likely blown also you can remove the radiator filler cap and start the engine, if there are any bubbles coming up in the radiator bottle this is also a pretty sure sign that the head gasket has blown. Not a cheap job to repair. Hope this helps.
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 a straw LOL, or flush the raditor with fresh water, keep doing it for 15 minutes or so and hopefully should remove most of the oil. Bit of detergent might help to - but remember to ensure that all that is flushed out to.
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.