The SPOOLOGIC Turbo Oil Feed Line Fitting SL-350-051 is a direct-replacement oil feed line fitting for 5.9L Cummins 12V (1989-1998) applications. Built to OE form and fit, it threads into the block and provides the oil-passage interface for the turbo oil feed line. Ships complete with the sealing hardware required to complete the install in one job. Backed by a 1-Year Limited Warranty.

Why You Replace the Fitting — Not Just the Seals

Oil lines and their sealing hardware are not designed to be reused forever. Here’s what’s actually happening to the parts you’re tempted to put back:

• OE feed-line fittings corrode into the block. The old fitting is usually crusted with oil coking and rust by the time you back it out. Threading a new line into a corroded fitting risks cross-threading the block — a fresh fitting torques cleanly the way the factory designed it.
• Feed-line fitting O-rings are single-use. The O-ring on the fitting takes a permanent compression set the moment it’s torqued down. Reused O-rings weep pressurized oil onto the exhaust manifold.
• Restricted fittings starve the turbo. The oil passage inside the fitting is machined to a specific diameter. A partially blocked or worn fitting drops pressure at the turbo center section and eats the bearings.

Component Breakdown — What Each Piece Does

• 1 turbo oil feed line fitting — machined steel fitting with the correct thread pitch and seat geometry for the 12V block port.
• Pre-installed O-ring — seals the fitting to the block port.

Material Technology — Why Each Material Was Chosen

• Formed steel line body — the line is bent to OE geometry so it clears the surrounding components and drops into the factory brackets without modification.
• OE-spec sealing hardware — the included crush washers, O-rings, or gaskets are the correct material and durometer for the oil temperatures and pressures this line sees in service.
• Heat-treated steel bolts and fittings — every threaded fastener in the kit is the correct grade, length, and thread pitch for the port it goes into.

Install Notes

• Clean the block-side threads with a lint-free rag before threading the new fitting in. Coked oil residue in the threads will keep the O-ring from seating.
• Install the new O-ring dry — no RTV, no thread sealant on the O-ring face. Lightly wet with clean engine oil so it slides into the port without rolling.
• Thread the fitting in by hand first — never use an impact. Cross-threading the block port ruins the block.
• Follow the OE service manual torque spec for the fitting. Over-torque cracks the block port; under-torque leaks.
• Inspect for oil leaks after a full heat cycle.

What’s Included

• 1 turbo oil feed line fitting with O-ring

Interchange / Cross-Reference

• Cummins OEM 3919687 — cross-reference

Features

• Direct-replacement oil feed line fitting for 5.9L Cummins 12V (1989-1998) applications
• Ships with the sealing hardware required to complete the install
• OE form and fit — direct replacement, no modifications
• Backed by a 1-Year Limited Warranty

Fits 1989-1998 5.9L Cummins 12-Valve

• 1989 – 1998 Dodge Ram 2500 3500 5.9L Cummins 12-Valve

1-Year Limited Warranty

Every SPOOLOGIC turbo oil feed line fitting is covered by a 1-Year Limited Warranty against defects in materials and workmanship from the date of purchase. Warranty covers replacement of the part only. Warranty does not cover labor, towing, downtime, consequential damages, failures caused by improper installation, failures caused by dirty or damaged mating surfaces, reuse of any included O-ring, or use outside the listed fitment.