Any shop that builds hydraulic hoses can fabricate a duplicate of that line, using the original as a pattern. I'd suggest that you find a shop that services construction equipment such as bulldozers, backhoes, forklifts, etc. Some NAPA parts stores are able to fabricate lines like that. "Single Braid" hydraulic flex lines are rated for 3K PSI pressure, far more than an engine oil system can ever produce. Hydraulic lines are measured in 16ths. of an inch, so that one appears to be a #4 or #5 line.
Jerry