I totally concur with grumpy, that seems as it has had ethanol as a mix from sale or post mix. The yellow colour is the begining of oxidition (due to water content) but the oil beased fuel has stopped it hence the yellowing colour.
ethanol is good when fresh, if left for a time (6 months plus, you need to get a fuel additive or drain all the fuel.
for long term storage use the bare bones all oil based fuel as the more you refine it the more extras are just going to break down and casue problems.
Peter
