Even if it's got alloys and LED washer jets?

And driven by a pimply sub 30 year old with a baseball cap on the wrong way round and a stereo system worth more than the car?

It could have sand in the engine for all the driver cares...

Although a 30 weight oil isn't optimal for lubrication, it gets round a bit easier.

A 5W30 isn't a 30W oil-it's fundamentally a 5W oil with viscosity extenders to bring the viscosity of the oil up to the samerange as a straight 30W at operating temperature.

I would imagine that the 5W/30 would work a bit better under most circumstances.

From a cold start 5W30 and 5W40 have the same viscosity. At operating temperature 5W30 is thinner than 5W/40.

In petrols, the difference between multigrade oils and true straight weight isn't that significant, but in diesels, the viscosity of multigrade oils can temporarily drop sharply under high pressures and lubrication can become marginal. To an extent, this problem has been overcome with advances in tribology. But you'll still find the HD diesels running on 15W40! They don't trust the thin stuff.

Yes unthrottled enjoys telling me the 240bhp in my car is rarely used nor required.

But my 240bhp Jaguar can sit at 95 i mean 70...70...Seventy...seven-zero, as thats the fastest you're allowed to drive in Britain, without even thinking about it. A little 40bhp s***box will have its valves putting on a production of the lion king on the dashboard at that speed.

Thanks for this useful information.