You will need:
A Pela 6000 oil extractor (or similar oil pump device)
4 Litres of Mobil1 0w40 or equivilent
Engine oil flush (optional)
Smart oil filter and seal
An oil drain can
Paper towels
27mm socket and wrench

Step 1:
Warm your car up to 80 degrees (Three blobs). Wait for 5 mins, then open up your boot, lift the carpet and open the engine cover. If you're NOT using engine oil flush please skip to step 3.

Step 2 (Engine flush, optional step):
Follow the instructions on the engine flush, most will be the same, you have to pour the flush into your oil filler cap and run the engine at idle for 10 to 15 mins, or go for a drive around for approx 10 mins, just follow the instructions. If your oil is already at maximum you may need to remove some of it using the oil extractor to make sure you don't go over the max mark.

Step 3 (Oil extractor):
Pull the dipstick out, wipe clean with a paper towel and place to one side. Push the semi-rigid pipe from the extractor into the dipstick until you feel it hit the bottom of the sump. Start pumping (on the pela you only need to pump about 15 times) and you should see oil rush up the pipe into the bottle on the extractor. You may need to give it extra pumps to get it all out, but you should see the pipe go clear again as it finishes, you might want to give a few extra pumps again and wiggle the pipe around to make sure all the gunge has gone from the sump.

Step 4 (oil drain can, 27mm socket):
Place the oil drain can under the oil filter cover, and using the 27mm socket undo the oil filter cover and remove it by hand, you'll get about 200ml of oil out from the filter and cover. Wipe down the cover, yourself and anything else you got oil over and discard the old filter and seal (at your local household recycling center).

Step 5 (oil filter and seal):
The new oil filter should click into place in the oil filter cover, and wipe a bit of new oil around the seal to form a good fit and place that back in the oil filter cover. Screw back the cover till it's hand tight, and nip it up a bit with your 27mm socket to make sure it's seated.

Step 6 (oil):
Pour in the new oil through the oil filler until you've put in approx 2.5 litres (there should be markings on the side of the bottle). Replace your dipstick and check the oil. Keep checking and filling until you've filled it to just below max. If you over fill it, there's a neat trick you can do with the oil extractor I'll tell you at the end.

Step 7:
Once it's full to max, replace the oil filler cap and dipstick, wipe off any oil you spilt on the engine, and get rid of the old oil now in your oil extractor at your local household recycling centre. You can now put the engine cover back in place, and put the carpet back down.

Hints
If you over-fill, take the dipstick out and place your oil extractor tube so the end of the tube lines up with the max mark on the dipstick, then mark on the extractor tube where the top of the dipstick is (the part that hits the top of the dipstick tube). If you put the oil extractor tube into the dipstick hole, then line up your mark with the top of the tube, you can suck out all the oil till it gets to maximum.

Please remember, when checking oil, you should only check your oil when your engine is warmed up to at least 2 blobs on the dash, ideally 3.

A quick word about oil.
Smart recommends that you use 0w40 Mobil1 Fully Synthetic. If your car is aging somewhat and tends to use up oil, you might want to try a thicker oil such as 5w40 or 10w40, please only use fully synthetic, and preferably the best you can afford, check your smart manual for oil recommendations.

Please do not pour oil down the drain, in rivers, or anywhere else that it shouldn't be, it harms wildlife, contaminates the sewerage system, and can get into the water table, take it to your local oil recycling centre.

As ever, we do not take responsibility for any damage you cause to your car while attempting the above procedure. If you break it, it's your own fault.