My 2000 S70 has about 67K mostly highway miles on it and I just got back from the dealer. I noticed it knocking shortly after I got it and switched to 89 grade gas but then the colder weather set in and I didn't notice whether it continued. This summer it was worse so I switched to 93, with no improvement after several tankfuls of mostly highway driving. It does it on acceleration between 20-30 mph. They didn't know what to do besides put some Techron in and charge 0 for the 60K miles service (fluids, plugs, filters, stuff like that.) It's my understanding and experience that modern engine management systems don't allow knocking to persist. I have run 87 octane in my '93 850 for 8 years without pinging. Anyone with experience with this out there?? It doesn't seem like this is normal behavior. This engine has the VVT, which they also claimed has solid lifters, after I mentioned that I thought they were noisey. Is this true?? G.Cook
