Each radio unit has a different code as a means of preventing them being stolen (or, at least, making them worthless if they were stolen). The best place to start looking for that individual code is inside the owner’s manual. Often, the dealer that sold the car new will have recorded the code, say, on the back of a business card or somewhere inside the manual or its folder, for future reference. And, yes, recording the code somewhere in the glove-box does tend to negate the value of having a secret code in the first place.

If you can’t find the code there, my understanding is that the dealer who sold the car new (information that should also be in the owner’s manual or service handbook) will have a record of all the codes to all the radios in cars sold by them. The catch is that you have to know the serial number of the actual radio before this can be checked. To do that, the radio will need to be removed from the dashboard and the serial number noted.

Premium diesel fuel seems to be one of those things that marketing departments, rather than engineering departments, have invented. It enables the fuel companies to charge you more for a product that is allegedly better, but nobody really knows why Premium diesel is an advantage.

At best, Premium diesel will have a few extra additives to help keep the engine clean inside, so maybe running a tank of Premium every now and then isn’t a bad idea. It won’t hurt. But don’t be fooled into thinking that your car will perform better in any meaningful way by switching exclusively to the more expensive Premium brew.

This is, of course, the opposite of Premium unleaded petrol which, depending on the car, can be a difference between happy motoring and expansive engine damage.

It’s not unusual for the steering wheel to wear, and your car is now nine years old, so I doubt you would get any help from Hyundai. Go to an auto retail shop, such as Autobarn, Repco, Supercheap, Auto Pro, or one of the many others, and ask for their assistance in treating the wheel.