I just broke down my 8b 2.0 and noticed my jx.21 is gritty when I spin the flywheel with plug out but only in one spot. It still spins pretty smooth but hear a little grit when I hold it to my ear so can I get some more races out of it or should take it out now and have rebuilt or keep it as backup it has about 6-7 gallons on it. I have a new Losi/Nova R21 Nitrotec but I can only get Odonnell Speed Blend 30% and friends say I should wait until I can get some Byrons 30%/11% for R21 break-in but I would really like to go ahead and use Odonnell because it's easy for me to get at LHS. What would you guys do? I have big race in two weeks and I doubt I can get fuel and broke-in unless I just use the ODSPBlend or just keep running jx.21. Thanks for any info/help!