A (not) oil question - a temporary bonus or not
 

I'm about to change the (very old) engine oil for one of the MA2 etc recommended ones + filter. But before checking things out on this forum and buying the "proper" oil I had a rush of blood to the head (that thing between the ears, not the other one) and bought a standard petrol car engine mineral oil 15W40 - I did say BEFORE checking things out on this forum. Thankfully, it's still in the jug at the moment, but knowing I'll probably never use it for anything else, I was wondering whether instead of just ditching it, I could put it in the engine and run it for say 100 miles to flush out all the 10 year (yes, ten years) old oil that is currently in there - I could then drain it again and put the new "proper" oil and filter in. On the jug the "fuel economy" rating is 0 stars out of 5 which probably means there are none of those additives that can cause clutch slip problems. The label has no MA/MA1/MA2 rating, just API SL/CF and ACEA A3/B3. I'm hesitating whether over a period of say 100miles whether it could cause any problems, or would the temporary flushing serve a useful purpose without the risk of creating any problems. Any views folks? For the sake of completeness, I can't be sure what the current oil is as it's been stood in the garage for 10 years and I can't remember what I put in all that time ago - but it's entirely possible it too was "non-compliant". Just as well its only had about 1000 miles put on it over the past decade. Thankfully, she's being better looked after now - due in no small part to this forum.

I wouldn't, the friction reducers will still get plenty of time to get into your clutch.

Flush with diesel if you dare, but you're much better off just putting in fresh Rotella T6 and a new filter.

It's not Rotella I've bought - I can't get that here in France. In fact, I've plumbed for a Motul oil as it's readily available. But the question is whether I should "flush" with the petrol car mineral oil or not. And I hear you're on the "no" side. Thanks for that. Any other views - for or against?

I would advise against using anything other than the recommended type.
I understood what you are trying to accomplish but you are better off not using other types. Just ny opinion.

So far, that makes 2 "no's" and zero "yes's". It's not looking too good for the car oil but I wish I could remember what oil I put in 1000 miles ago as I might be a little less hesitant if I knew it was "non-compliant" since it didn't cause any problems over that usage. If I end up not putting it in the bike, maybe I could fry my chips in it.

Look at it this way. Your goal is to flush out the old oil. If you use a non-perscribed oil you will need to flush that out as well.

The only thing you will harm is the clutch plates, due to the antifriction and more work down the line, if slipping.
An oil change, if you are doing it, it's cheap insurance, but the peace of mind will let you sleep until the next oil change needed.

If the jug isn't opened maybe you can take it back for a refund? Where I'm from 15W40 is used for diesel engines and has a ton of anti detergent additives. Never thought about how using the wrong oil could affect your clutch plates - Good to know. I pay the long dollar at the Honda dealership which isn't frugally smart but don't have to worry about getting something not designed for my bike.

"Good stuff" is in
 

I've just put the Motul oil in and I'll be keeping the other oil for, well, I don't know yet (can't take it back as the receipt is long gone). Better to have peace of mind, rather than "flush with non-compliant oil" and then be constantly worrying and listening for non-existent problems. Managed to get the oil filter off and a new one on without taking any fairing off - a minor recompense. Thanks for the views all.

NEVER, EVER put anything like STP or other slick oil treatment stuff in there. Your clutch will slip so much that you won't get out of your driveway.

I would have been a yes on the oil type to flush it. If you're just flushing it, I'd have gone maybe 50 miles or so. After say 300 miles the transmission would crush the lubricating spheroids to the point that the oil had the viscosity of water. After flushing the oil would have been unusable because it was getting shredded by the gears and would have the 10 year old sludge mixed in.