I currently have a Redmax BCZ2460S and run quality synthetic 50:1 oil with 93 octane ethanol free fuel. My issue with it is a rattle sound at the first start of the day (which takes 5 or more pulls) and the rattle sound gets bad when at or near WOT and it doesn't matter if I'm cutting anything or not but it tends to sound worse when trimming thick grass. I've had it for less than 5 months and the dealer isn't really willing to help me much without a charge to look at it and Redmax said that it probably wouldn't be covered under warranty since I'm not using Redmax maxlife oil. I use Get G's two cycle oil which meets or exceeds the rating that Redmax recommends in the owners manual. My guess the issue is a bad connecting rod bearing/bushing. Its probably been doing the rattling sound since it was new but I didn't do any heavy trimming or do any or near WOT stuff until I took on a few bi-weekly lawns that were super over grown. I've already checked to see if the muffler was rattling or anything is loose on the trimmer but everything checks out fine so I'm almost 110% the noise is coming from inside. I'm considering the Stihl FS90R since thats all I really need power wise for weekly and bi-weekly trimming. Mainly around the house, fence's, storage buildings, and a lot of edging. I've never owned a 4 mix trimmer and I would plan to use it as my primary trimmer and use the Redmax as a back up. I have a friend who loves the Stihl 4 mix stuff and swears by it so I'm pretty sure that it wouldn't be a bad idea to get a FS90R but wanted to see what you guys think. Its sad that things aren't built like they used to be. Any opinions?