i run fphe year round, no problems. Yes loop your return it is worth the extra cost in saved filters. I do have a shut off valve for all coolent flow to veg system so i could fill up with diesel if i don't have any vo

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2011 e320 cdi (132,000) current
2005 Jeep CRD diesel--2.8L (138,000 miles) wrecked, insurance took
1993 Mercedes benz 300D 2.5 Turbo Frybrid powered. (336,000 miles) wrecked and sold as parts car
1990 Mercedes benz 300D 2.5 Turbo (170,000 miles) wrecked and sold as parts car

Check out my Frybrid Vegtable Oil Conversion at http://1990300dfrybridconversion.shutterfly.com/