I first replaced mine with factory lines but when they started to weep, I replaced them with transparent blue ether based polyurathane lines from McMaster.com. Cheaper than factory and so far have lasted twice as long as factory.

__________________
Ron Schroeder
'85 300 Turbo Diesel 2 tank WVO
'83 300 Turbo Diesel 2 tank WVO
Some former WVO vehicles since ~1980:
'83 Mercedes 240D
'80 Audi 4000D
'83 ISUZU Pup
'70 SAAB 99 with Kubota diesel
'76 Honda Civic with Kubota diesel
'86 Golf
Several diesel generators
All with 2 tank WVO conversion
LI NY

Napa carries 1/8 " fuel line that will work well for return lines. Says not for fuel inj on line but this means for high pressure. The return lines will run less than 8 psi. They are a bleed line for excess fuel from injectors and run thru the filter block back into tank.