i used to often suffer dry belt squeel on many cars . as all garages do just spraying a bit of WD40 often cures if for a while.. i found best cure was smearing some silicone grease on the belts and that helps them last a lot longer. but yes if any of the grooves are damaged or broken its time to replace it
I guessing the WD and silicone allow the belt to slip, but stop the noise,like tyres do not squeal on ice.....
When the old single V belts were made from rubber the petroleum based stuff like WD would degrade the rubber and make it sticky, stopping the squeal temporarily, but modern multi V belts made from polyurethane or synthetic rubber so not affected by oils, so any lubricant will just destroy the friction they depend on to do their job.
Thanks so much to both of you for your insight! I do also think its not that wise to spray wd40 on belts... Yeah maybe a bit just carefully on the turning mechanism of the pulley. (thanks for reminding me what they are called, not a native english speaker here) So yeah, will check tension, state of belt and potentially pulleys and also brand new Honda MTF3 in my gearbox! Hopefully she'll run for a few years like that!
Maybe last little point: like many Jazz'es there is a bit of rust on the back door and some little spots here and there. How do you guys tackle the rust problem on your Jazz? I do not mind the paint at all, my car is full of scratches and little dents anyway, im all about mechanics being ok. Beauty doesn't make you go from A to B. My guess would be a bit sandpaper, cleaning and then potentially spray a bit of paint and then protective coating? Im also looking into spraying the rubber suspension parts with this "rubber spray" that keeps the rubber soft and last longer to avoid leaking / suspension problems. Lastly maybe replace the pollen filter behind the dash storage (I think its there). That's pretty much it. (sorry for being off topic, this website is just too helpful and you all are very knowledgeable, i'm grateful!)