My son's volvo has a sludge problem, so I want to change oil. However, I am wrapped around axle with regards to oil weight. Considering the sludge problem, what oil weight should I use? It seems 0W30 or 5w30 are both acceptable, but which one is better in my situation? We live in the Baltimore/Philadelphia area, so we can get summer temps in the 90s, but only for a few days.

 

https://www.fcpeuro.com/products/pro...BoCBdsQAvD_BwE

This stuff works fantastic. I used it when I picked up my S60 used. Cleaned out so much crap.

I used 5w-30, also by liqui moly on all my oil changes on that car. I live in CT, similar climate.