Ive been using Valvoline import multi vehicle full synthetic for a year, seems fine

Just got a good deal, now I own a Volvo. I had a clunking noise, when driving straight, over slightest bumps. First thought CV, but that's more likely to clunk on turns. Then searched this forum and found it may be the strut spring seat. Swapped out both struts today. Sure enough the front passenger ...