Neophist and derek are right.. Car oil won't last in a bike.

Oil is made up of microscopic 'chains' of stuff and needs to stay that way to work properly. Unless you have oil with a high shear-strength (i.e. bike oil) the chains get sliced up by the gearbox and the oil loses its effectiveness.

Friction modifiers are a seperate issue too... They are added to car oil to to improve efficiency but will bugger a wet clutch.

A bit like a Mini then or any other of the numerous unit construction engines? What about the automotive engines with gear driven cam train?

Exactly....That's why you get special high-shear oil for those applications. Google 'Millers Classic Mini Oil': it's a high-shear oil designed for Minis for that very reason.

I guess the point is that 40 years ago anything slippery would do, but a car was toast after 100k miles. These days we match the oil to the application and engines last far longer. You could stick magnatec in a VFR and it won't explode, but it's not really the best thing to do.

I'm sure my Mille runs Motul 10w50, might be worth a look as it's a motorcycle oil.

Assuming you are getting 100+ miles to a tank, thats only circa 250ml/1000 miles.
I wouldn't overly worry about it.
Like suggested, maybe find a 10 or 15/50 grade mineral or semi synth bike oil.
I wouldn't use a mono 40 - it was designed for engines much older & less developed than the nc's!

Phil

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Why 10/50 over 10/40?

It's mostly likely going to be more expensive than a cheap 10/40 semi-synth bike oil.

Neosophist wrote:Why 10/50 over 10/40?

It's mostly likely going to be more expensive than a cheap 10/40 semi-synth bike oil.

Thicker when hot - may burn less

Phil

being honest with the miles you probably do offset against the cost of sorting the issue I'd just put up with a little oil consumption and the inconvenience of having to top it up once in a while.