Oil change - will this cause issues?

[Slaninar]

Affordability? At that particular time in my life, money was non-existent. To the point I was using 2nd hand tyres on the GS650 I was using at the time (removed from Police BMW's with 5mm + tread left), in order to keep riding to be able to get to work savings had to be made. You obviously did not read the rest of the post, with regards to the lack of issues based on the experiences gained whilst not spending money, which I did not have at the time.
To really wind you up, I semi - retired that particular machine in 2002 with around 65,000 miles on the clock - most of which had been done with car grade 20W50. As I cannot leave things alone, I have stripped the engine to find the internals in very good condition for a machine built in the 1980's. It will be going back together as a resto project and I will be putting whatever oil I choose in it, as it is my choice, based on my experiences and my skills as a qualified aircraft piston engine engineer. (And that qualification and experience covers Radials, Rotarys, Flat 4's, 6's & 8's, Inverted in-lines, V's, Air & liquid cooled, Wankel rotarys, in both 2 stroke and 4 stroke styles!)
I will more than likely, do as the OP asked, as I can now due to being in a better place, put a poor quality oil in and use it as a "flush". It is a good idea. It is unlikely to harm anything unless it is full of the friction modifiers which have been mentioned in earlier responses. :lol

I've lived most of my life in a country with an average monthly pay of under 400 euros (most of the time below that number), and still find it a bad economy to spare money on oil. We're talking about 10 euro price difference per oil change (unless prices in UK differ by a lot). I also don't see a point in saving some money per oil change, then doing oil changes more often. For all I know (not an engine engineer though), changing oil more often than specified does nothing to protect the engine better, unless it is a really bad quality oil - even then, the engine is better protected with a god quality oil, changed per manufacturer's recommendations for oil change intervals.

As for engine wear and protection, I doubt that car oil does as good job as a good quality fully synthetic motor bike specific oil. Again - at really minimal savings.

My oil of choice is Motul 7100, 10w40 grade, and so far my Fazer has only about 70.000 kilometers and no noticeable/measurable oil consumption between 6 to 10 k km oil changes (depending on mileage).

Until I see a parallel test of two engines run on a car and motorcycle specific oil, I'd rather not risk it.