Use 15w/50 mate. Mobil one, silkoline, or valvolines well cheap for the money only 15.00 quid for 5 litres.

As for the 5w/40 thats what came up at halfords when i went only to find the didnt have what i want. Im running 0w/40 in mine at the moment but not really caining it about as it badly needs a tune and im doing a rear disc converison. To be honest the engine does tap on start up but when it warms up its all good in the hood or under as the case maybe. But why be a noob like me, get the proper stuff. I just dont want to pour 40 quid down the drain.

But when it comes to the time i go for a rolling road. It needs to be changed to 15w/50.

I bought mine of ebay there is mobil 1, valvoline and siloline on there. Or use oilman.