What oil grade are you using on your 900ss or 750 Sport..
Only thinking about this as on its last service the Ducati specialist used a 10w40 which I know is correct on the later bikes, but on my F1 the recommended oil is a 15w50 and I seem to recall this is correct? More as the bike is only used in summer....

A subjective subject, but this makes a interesting read, Norton related but maybe not a million miles away from our Ducati’s ?
https://www.accessnorton.com/Oil-Tests/NortonOil.php#3

I've always used 10w40 in the 907 and previous Ducatis until I bought a 1200 MTS. It and all newer Ducatis, including my Scrambler and Supersport, use a 15w50 so Ducati must have a re-think about oil. I'll probably move them all to 15w50 as it will save me buying 2 grades of oil.
I use this 10w40 in the 907
For the Scrambler I use Silkolene Pro 4 15w50 XP
The Supersport is still under warranty so has been dealer serviced with Motul 300V 15w50 up to now.