met al ▁ox ides ▁can ▁be ▁de grad ed ▁when ▁b iod ies el ▁los es ▁its ▁stability ▁caused ▁by ▁ox id ation . ▁Comm only ▁used ▁synth etic ▁rub bers ▁FK M - ▁G BL - S ▁and ▁FK M - ▁G F - S ▁found ▁in ▁modern ▁vehicles ▁were ▁found ▁to ▁handle ▁b iod ies el ▁in ▁all ▁conditions . ▁ ▁Techn ical ▁standards ▁ ▁B iod ies el ▁has ▁a ▁number ▁of ▁standards ▁for ▁its ▁quality ▁including ▁European ▁standard ▁EN ▁ 1 4 2 1 4 , ▁A ST M ▁International ▁D 6 7 5 1 , ▁and ▁others . ▁ ▁Low ▁temperature ▁g elling ▁When ▁b iod ies el ▁is ▁co o led ▁below ▁a ▁certain ▁point , ▁some ▁of ▁the ▁mole cules ▁aggregate ▁and ▁form ▁cry st als . ▁The ▁fuel ▁starts ▁to ▁appear ▁cloud y ▁once ▁the ▁cry st als ▁become ▁larger ▁than ▁one ▁quarter ▁of ▁the ▁w avel ength s ▁of ▁visible ▁light ▁– ▁this ▁is ▁the ▁cloud ▁point ▁( CP ). ▁As ▁the ▁fuel ▁is ▁co o led ▁further ▁these ▁cry st als ▁become ▁larger . ▁The ▁lowest ▁temperature ▁at ▁which ▁fuel ▁can ▁pass ▁through ▁a ▁ 4 5   mic rom et re ▁filter ▁is ▁the ▁cold ▁filter ▁plug ging ▁point ▁( CF PP ). ▁As ▁b iod ies el ▁is ▁co o led ▁further ▁it ▁will ▁gel ▁and ▁then ▁solid ify . ▁Within ▁Europe , ▁there ▁are ▁differences ▁in ▁the ▁CF PP ▁requirements ▁between ▁countries . ▁This ▁is ▁reflected ▁in ▁the ▁different ▁national