I couldn't find a relevant sub so I thought I'd ask here. I recently bought a 2007 Aurion sportivo sx6 with 150,000 kms on it. I didn't have any issues during the first week but it soon developed the dreaded vvti rattle. Despite this is it drove well and could engage vvti (after 4800rpm) just fine. But recently I've noticed that once it exceeds the 4800 rpm limit and transitions into vvti there is a noticeable grinding sound that occurs that isn't present in any other portion of the rev range. Is the grinding sound a result of the bad vvti spring or could it be another problem. Ever since it's developed that noise I haven't really taken it beyond 4800 rpm. Just had a service done yesterday so decided to check whether the noise is still there, and it is. Is there an easy fix to this? And is it diy-able.
Also similar to Vix I was getting ridiculously poor fuel economy on 94 (around 15L/100km) but since then i've been using 95 and it's settled at 12L/100km. The previous owner claimed to be getting 9L/100km which I honestly find pretty hard to believe. Does anyone have any tips for helping reduce the fuel consumptions? Will using 98 make a big difference?