Which oil to use?

With the pathetically low mileage I am doing I seem to hardly use any oil in Pepé! But I like to keep it topped up. I have always used a semi-synthetic oil in all the bikes and a 10w40 range oil.

The manual isn't all that helpful:

So having a look on the API website SH is a well out of date specification.

I know the Rocket is getting on a bit in engine terms but SH is positively antediluvian in comparison!

A bit more poking about on the various websites or forums it seems that Triumph shifted from Mobil to Castrol oils,

Armed with a 25% off "friends and family" voucher from fellow  Meldrew, Trevor Rice, I checked out the Halford's webpage.

I have ordered Castrol Power 1 4T Motorcycle Engine Oil. It's £39 for four litres and I guess it's formulated for motorcycles. The 25% off makes it less painful.

Not being an expert I have no idea whether the modern turbo car engine is more or less oil conscious than motorcycles!  We were told in the 80's that motorcycles needed a different polymer build up in the oil due to the higher revs and engine design. Truth or bowlocks?

Next.  Book the MoT for the last week or so of January and pray that it's not as freezing cold as last year!