Nice to have some indicator of the rad going wrong before overheating on the road.
Sounds like good info, thanks David.

Very impressed with the simple Green help and service.
Simple Green Aviation Extreme arrived Saturday.
Radiator cleaned and test ridden today. I tried to ride similar lanes as when it got the six bars and it was also the same ambient temperature of 22.5c.
Result stayed at 3 bars when moving in clear air and no more than 4 bars in traffic and some high hedged lanes in 3rd at about 40mph but came down to 3 bars when moving freely on more open road.
I dampened the rad with a water spray bottle and brushed the neat solution onto the fins and then  50/50 mix from the foamer bottle ( glad I bought it) and also brushed that in, had a cuppa and washed with my little gizzmo of squashed copper central heating pipe with an 8th inch hole in it and attached it to my garden hose. This allows you to get behind the rad and run the single jet along the rows of fins.
Do the back first of course. I was amazed at the grit thrown onto my front mudguard.
All in all a success I think. Link attached.
https://simplegreen.co.uk/index.php/buy-simple-green-household-products-uk/extreme-aviation-1l

Thanks for that Costas.
I just like to use the recommended stuff so if something goes wrong I know its not the oil etc causing the problem.

Are the Ozzie rads compatible with the K1300s inside and out?
400 oz dollars is £230 according the currency site I found.
Isn't a new replacement rad around £400 in the UK?

Found this and thought it might be of interest.
https://www.k1600forum.com/threads/radiator-cleaning-maintenance-impacted-grit-sand-dirt-lessons-learned-radiator-fin-pick-and-floss-yeah-really.201550/

What bad things?
What happens to any excess oil if overfilled?
I made the mistake in Spain of filling at a fuel station a short distance from our hotel so it was cold. later I found it was overfilled but there were no consequences.
I understand the tank as a reservoir and only a set amount is allowed into the sump. The tank allows the oil to cool and the the less in there the more its used and visa versa.
As far as I can see the worst thing to happen would be overfilling when cold and on starting the engine pumps excess oil back to the tank and it wants to overflow but can't.
Come you experts and tell me the facts.

As Brian said, being able to wear a teabag jacket in the heat and put the EDZ on underneath when needed when chillier and have taking up so little space was a win win for me. But £90 for the Klim version is to my mind robbery.