"OEM" means the part was made by or for the manufacturer of the RV and is the same as what was fitted at the factory. "Aftermarket" means anyone else made it. Neither is automatically better. The right choice depends on what kind of part it is, and once you sort parts into four groups the decision is usually obvious.
Group 1: fitment-specific parts. Buy OEM.
These are parts molded, extruded, or cut to fit one camper: windows, doors, tanks, body panels, cabinet doors, dash and control panels, steps that bolt to a specific frame cutout. The aftermarket alternative exists, but it will be close rather than exact, and "close" costs you a day of trimming, sealing, and bracket-making.
Examples from the Black Series catalog: the replacement windows (double-pane acrylic with the fly screen and blind integrated, in ten factory sizes), the entrance door full assembly, the OEM water tanks, the HQ control panel, and diamond plate panels. For these, the price gap between OEM and aftermarket is smaller than the labor to adapt, and resale buyers can tell.
Group 2: branded components the factory bought in. OEM and aftermarket are the same part.
RV manufacturers do not make couplings, jacks, bearings, fridges, air conditioners, or inverters. They buy them. When the factory part is a Cruisemaster DO35, an ARK XO500, a Timken bearing, a Dometic fridge, or a Victron MultiPlus, the "OEM" part and the branded part you buy separately are identical. Buy on price, stock, and warranty.
Examples: the Cruisemaster DO35, ARK XO500, Timken 12 in bearing, Dometic CoolMatic CRX 80, and every Victron product. In this group the real question is whether to step up a grade (DO35 to DO45, XO500 to XO750, Orion-Tr to Orion XS), not OEM versus aftermarket.
Group 3: commodity parts. Aftermarket is fine if you match the spec.
Gas struts, hoses, clamps, fittings, LED lights, switches, fans, pumps of standard footprint, detectors, water filters, faucets with standard connections. These are made to specifications, not to a camper. The OEM version is often a commodity part with a label. Match the spec (length and force for a strut, flow and pressure for a pump, voltage and lumens for a light, thread type for a fitting) and the aftermarket part is as good, sometimes better.
Examples: the window struts are sold as OEM and priced like a commodity ($25.00 a pair) because they are one; the 12 V water pump fits far more than Black Series campers; the 12 V LED touch puck replaces the factory light on any camper with a 70 mm cutout; the HepvO trap is an upgrade over most factory P-traps.
The trap in this group is spec creep: a strut that is 10 mm longer, a pump with a different port thread, a light with a different color temperature. Measure, and read the listing.
Group 4: safety-critical wear parts. Buy the brand you can trace.
Brakes, bearings, breakaway systems, couplings, safety chains, propane regulators, detectors, tires. The aftermarket is full of parts with no traceable manufacturer, no published ratings, and no warranty. Price is a poor guide here because a cheap magnet or bearing costs the same as a good one until it fails on a grade.
What we stock and why: Timken bearings because they are traceable; the CURT breakaway kit because it has a tester built in; Dometic Atwood and Flame King for gas safety; complete electric brake assemblies rather than loose shoes and magnets of unknown origin.
Three examples where people get it wrong
Buying an aftermarket window to save money. The aftermarket window is $150 cheaper and 12 mm smaller. The owner spends a weekend making a filler frame, the seal never quite sits, and the camper leaks at the first storm. The OEM window would have been in by lunch.
Paying OEM prices for a commodity. A dealer quotes a "genuine" 12 V puck light at several times the price of the same 70 mm touch light sold without the label. Same cutout, same connector, same LED. Group 3; buy on spec.
Buying no-name bearings to save $10. The set arrives with no manufacturer marking and no grease specification. One runs hot on the first long day. The Timken set was $29.00. Group 4; pay for traceability.
Warranty and support
An OEM part usually carries the RV maker's parts warranty; a branded component carries its maker's (Victron publishes its own); a commodity part carries whatever the seller offers. Our warranty page explains how claims work for each brand we carry. The practical point: for a part you will rely on for years, the ability to get a replacement under warranty from a company that will still exist matters more than a 15% price difference.
Resale
Buyers of used off-road campers look for original windows, doors, panels, and couplings. A camper with a mismatched aftermarket window or a non-standard coupling sells slower. Groups 1 and 4 are where OEM or brand-name parts protect value; groups 2 and 3 do not affect it.
A decision rule in one line
If the part is shaped for your camper or your life depends on it, buy OEM or a traceable brand. If it is a commodity, buy on spec. If it is a branded component the factory bought in, OEM and aftermarket are the same thing.
Shop this
- Black Series HQ Camper Parts (Genuine OEM) (collection)
- Universal RV Parts (collection)
- Cruisemaster DO35 with Handbrake — $389.99
- Black Series OEM Window Struts — $25.00
- Big Bearings, 12 in Timken — $29.00
- Victron Energy (collection)