Yes I was on many forums in Europe, Hong Kong and here I'm 16 years member.
Problems with deposits on friends Volvos especially in Italy where we regularly participate meetings from 2015 ahead shows huge deposits inside especially tractor diesels as I call this engines hahaa
Seriously if you check caracteristics for Volvo engines and dummy 30.000 km to change come on??? I change every 10k max.was happened 12000 km on petrol 2.5t engine and diesel wait tooooo long...
Same happened last 15 years when Lolvo say No need to change Atf oil life time...than US where protection is high made few court cases and lemon Lolvo corporation changed idea...
From first oil change Volvo service didn't want to change me oil in engine with Mobil saying guaranty bal bla...
Same with trans.
Than I start changing and trust me I really drive too fast last 17 y. And 2.5t engine is done for. Diesel tractors is to slow motion pulling some trailers on long distances some horses camping pigs ect...
Castrol oil I can post you photos of PCV and Pipes and Turbine blowing with Castrol 0w30 that VCC raccomend it. But for low pressure turbo and engine this is not good oil to cool properly Turbine in high revs and high temperatures that was.
Later will post photos before and after.
Castrol 3w30 vs. Mobil 5W50 is incomplete oil for Turbine. I'm not expert mechanic or oil ect but practical experience I have is this:
After Turbine blow away and on Highway this day no more mosquitoes was on TV news
My mechanic the best in Slovenia Bauman near town Maribor ordered
EXCHANGE VOLVO PARTS that at first I was against gipsy recycled refurbished old not mine parts but now I made over 200.000 km with this new Turbine and of course Mobil 5W50 that properly cooling high temperature on bearings when I pushing 235 km/h on German highway hahaha max speed.
Average in Slovenia Croatia Serbia is 160km/h limit is 130. Once a 5 year pay fine but enjoy.
Sorry for long post but there is the better oils than crap Castrol.