OEM or Aftermarket


This article is a reprint form MarineEngine.com's January 24th, 2014 newsletter

A question we are often asked is "Which is better, Original Equipment Manufactured (OEM) or Aftermarket parts?"

When you take your boat/motor to the dealership's service department for repairs you're probably getting Original Equipment Manufacturer (OEM) engine parts.  However, if you take your boat to an independent shop, you'll most likely get aftermarket parts.  Is there anything wrong with that?  Does a less expensive part mean a part that's lesser quality?  And in what situations should you use only OEM parts?

An OEM part is a part sourced by the manufacturer of an engine. OEM parts will be the same as shown on your engine diagrams, or as superseded by the manufacturer.

An aftermarket part is any part that is not sourced from the original engine manufacturer.  Notice I did not say "made by the engine manufacturer", because in many cases the OEMs are sourcing parts from other vendors in the same way the aftermarket automobile companies do.  All the major aftermarket manufacturers make parts designed to function as well OR BETTER than the original, and they will meet or exceed the design specifications of the original part.  If the aftermarket part is a direct replacement of the original part it will not void your engine warranty.

Let's look at the Pros and Cons:

Aftermarket Parts Pros:

Cost:  Aftermarket parts are usually less expensive than OEM.  The amount you save will vary by part and by brand, but you can often save 20 - 40% as compared to OEM.

Quality:  Many people assume that the lower price of an aftermarket part means the quality will be lower.  That is usually not the case.  Quality and reliability for aftermarket parts from the major manufacturers are as good as or better than the OEM.  The aftermarket companies are able to analyze the strengths and weaknesses of the original part through the reverse engineering of them and often are able to work out any bugs that had developed over the years from the original parts.  We see numerous cases where certain aftermarket parts are undoubtedly better.  An example would be powerpacks for the Johnson/Evinrude 1992-2006 150 and 175HP 60 Degree Optical (OIS 2000) Carbureted Engines.  CDI Electronics kit 113-6367K 1 is a definite improvement over the original OEM powerpacks.

Better Availability:  Aftermarket parts are available at more of our locations and can usually be delivered to you more quickly.

Warranty:   Contrary to what many consumers think, the aftermarket manufacturers generally have a better warranty on their parts than the OEM does.  They need to offer a better warranty in order to overcome the consumer concern about buying aftermarket.

Aftermarket Parts Cons:

Quality Can Vary From Some Manufacturers:  Stick with the major manufacturers of aftermarket parts to ensure consistent quality.

Overwhelming Selection:  Sometimes it seems confusing to choose the correct aftermarket replacement.  When in doubt check the manufacturer's application guides and catalog data.  You can also use MarineEngine.com's automatic cross-reference, by entering the OEM part number in the Part Number Search box near the top of the page.  For example, searching on 47-803630T, a Mercury/Quicksilver Impeller, will yield both the OEM and corresponding Aftermarket parts.

OEM Parts Pros:

Easier to Choose:  Your original part number as the OEM part will be the same as shown on your engine drawings, or as superseded by the manufacturer.

OEM Parts Cons:

Cost:  The OEM parts are almost always more expensive, although some of the engine manufacturers are feeling the pinch and are trying to offer matching pricing on the fast moving parts that are available as aftermarket.

In our opinion, when you have a choice, the correct aftermarket part from a reputable manufacturer will be your best option, although there are many parts that are only available as the OEM.  The marine engine parts business is a small market as compared to the automotive market and there are many parts that are just not worthwhile for the aftermarket manufacturers to produce.

We give you a choice of OEM or aftermarket parts for Johnson, Evinrude, OMC, Mercury, Mariner, Force, and Mercruiser.  Searching our site using either the OEM or Aftermarket part numbers will give you both the OEM part as well as the available aftermarket parts options.  Quality aftermarket brands we carry include Sierra, CDI Electronics, ARCO, Barr Marine, Solas, and Wiseco.  You decide what's right for your motor!

Andrew Menkart
President - MarineEngine.com

Note from the author of this website ---

 Aftermarket parts will not be available in the extent that you would expect from a full blown authorized outboard manufacturer's dealer.  This means it is similar to automotive part stores, where you can buy a radiator but not the hood, or transmission bearings but not the whole transmission.   Relate this to outboard motor parts.  NAPA also sells aftermarket marine parts.  Their catalog is the same as the Sierra catalog.  In these, you will find head gaskets, but no heads, or water pumps/impellers but not the complete lower unit, carburetor repair kits but not the carburetor itself.  You may find replacement pistons and rings.  And of course no cowlings or mounting bracket parts.  Generally what you will find is simply normal repair parts.

OEM parts from the manufacturer in excess of those mentioned above can be available for a reasonable period of time, however do not expect to be able to buy or even order a cowling off a long obsolete 1980 15hp Johnson.  It appears that for obsolete parts (or soon to be) the manufacturers take a look at their inventory and as the inventory goes down, the price goes UP.

Some manufacturers use specially built items that no other manufacturer ever even thought to use (Mercury for one).  Any part that is out of production, you may need to take 2 of your heart medicine pills before you ask the price.  And if you just need a fuel filter gasket, you may have to buy the whole filter assy.

For long obsolete parts, you will need to search out marine salvage yards.


 Reprint of MarineEngine.com  January 2014 newsletter

2014 - 2017 LeeRoy Wisner

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Originated 01-24-14, Last updated 05-28-2017
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