97 with engine knock

New to the forum. I purchased my 97 Suburban with 85K miles and it ran fine until around 95K when it began having a knock in the engine. I changed to higher octane (93) gas and it appeared to help for a while. However, now at 108K still using the high octane, the knock is back. It is not as loud or as long but still there. I have also tried the fuel injector cleaners and boosters but those don't seem to make any difference. We also own a '98 and know many others with the same 96-99 models who do not have to use the high dollar fuel. Any ideas?

Thanks
Red

I started having the same problem recently in my 1999. I thought it was coming from the top of the engine. turns out it was coming from the bottom. after investigation, turns out that the local speedy lube place was putting 10-40 oil in it during oil changes. after checking with the tech advisor at the dealer, I found out this is a big no-no. the dealer advised to use the oil as specified on the oil cap. what a difference !