I have recently purchased a 1978 BMW R100S that was to run on leaded fuel. The previous owner used a lead replacement. I have Neutra 131 already at home but wonder if I should use 131C Soy Neutra or the 142 Valve sheild. I also should tell you the BMW is a bit higher compression and the benifit of Soy Neutra may help. I want to take in consideration first: lead replacement 2nd: fuel enhancement as far as octane/combustibility goes and 3rd: fuel stabilization due to the fact the bike will sit during cold months for a time. Thanks for your help, Gary.