Car Doctor: Essential oils, nasty noises and plate procedures

Could you tell me if the 20-50 grade motor oil sold in supermarkets is any good? Would it be acceptable for my double overhead-cam 2.0 EFI 4X4 Sierra Estate?
JU, Salford

Could you tell me if the 20-50 grade motor oil sold in supermarkets is any good? Would it be acceptable for my double overhead-cam 2.0 EFI 4X4 Sierra Estate?
JU, Salford

You should only use engine oil which matches the specification required for your vehicle and I am not aware of the specification of the oil you mention. The recommended oil for your car is Ford Formula E 5W 30 or equivalent, providing it matches the specification WSS-M2C913-A or WSS-M2C912-A1.

I have a 1999 Renault Clio that makes a graunching noise when starting from cold which only goes away once the car is warmed up. What's the problem?
BH, Farnborough

This could be a number of things and it all depends on how you describe the noise. A rumbling or grinding from the front end of the engine could be a worn water pump or alternator bearing. A persistent hard knock would be the big end bearing which would need an engine rebuild as would a rumbling rotating noise from the main bearings. A screech on start and when the engine is revved might be a slack fan belt.

How do I buy a private registration plate?
PQ, Lewisham

A number can only be transferred from a vehicle which is taxed and tested, or from a paper Retention Certificate where it can be held for an annual fee. Also the Driver Vehicle and Licensing Authority (0870 6000142) sell their "Select" range of numbers and also hold periodic auctions for valuable numbers.

You can also find dozens of dealers in newspapers and magazines. The transfer fee is £80. When you buy a number, a Certificate of Entitlement (V750) comes with it. Form V317 is required to transfer it to a vehicle and V778/1 allows you to retain the number if you sell the car. Contact your Registration Office, the number is in your phone book.

*Write to Car Doctor, Features, Independent House, 191 Marsh Wall, London E14 9RS, or e-mail cardoctor@independent.co.uk