sashaa

Oil leak and gasket are associated to each other. You didnt mention which oil is leaking. If engine oil then crank case gasket, engine housing gasket, chamber gasket are gone and need change. If gear oil then its lot easy and only one gear gasket to doubt.

See electrician and let him check the wiring connection under the seat, some got loose or plugged out. Before that check all fuses by yourself if some got burnt.

You can any gas that is Made in US or mexico or france. They are good gas. DONT USE CHINESE ones they will spoil your compressor after few months.

yes of course, i suggest DO NOT DRIVE. Take to good mercedes specialist on recovery. Sorry but it looks its from crank case, does this noise comes always even on IDLE and get increase when you give gas then crank bearing or something inside engine is chipped or broken. If same on idle and when you give gas, it could be from tappet cover of adjusting the valve or lifter issue.

Seat belt have actuator inside the belt, you can't repair it you have to change the seat belt only.

If car in warranty let Gargash diagnose and comment. If not go to Mercedes r us in rashidiya and ask them to check it. Without checking its difficult to comment bro.

Many things. Is car been regularly serviced. If yes then start with Spark plug Plug wires (HT leads) Fuel supply (fuel pump)

40k km.

Under the cover there are flat bed clip put minus screw driver and open the clip and remove, by simply pulling you broke it.

100% ceramic is better, but its just 4 times expensive than normal ones. Im sure now u knw what to buy.

In ACE hardware u can get best one is Meguir's approx 50 aed for bottle. Thats awesome.

Go with OEM spark plugs as per manual and dont worry abt gap. Its way to techy for all of us. If im not wrong gaping shud be 0.039 (double check with manual).

its time to change the changer, it must have served enuf dude. 12 years. Life of optical readers are less than 5 year. (no offence)

Is there any code needed in car for activating entertainment system? Just check.

by the remote while child seat is activated.

what are the pricing with all super duper discount?

Check the door beading from wherever hissing is appearing, B class insulation isnt very good too. But hissing is surely from the door beading, identify the leak and try putting silicone inside the beading. Before that test that leak by coveing beading with tissues and drive if it stops. once confirmed permanently seal it with transparent silicone.

To identify the source of problem is quiet tricky. Usually any drive than 20 mins is required to keep battery charged, if you are running everyday less than that in sometime battery gets weak and dies. That could be the case here. To identify the main issue wether its some electronic causing this drain there are two ways. 1) Drive your car for 2 hrs and let car sit for 3 days and see, if it starts that means battery isnt getting fully charged ever. If it fails that means something draining it up. 2) loan a battery from friend and leave for three days and start, if it starts then its your battery is dying and if that battery also fails then its something draining up the battery (even more difficult to trace) Chances with 1) option is less as ur current battery might be already weak to hold charge for so long, so try for 2) option if it fails and let us know here.