Honda Outboard Spark Plugs-Saving a buck or 2

I emailed a Honda Service shop/dealer and asked if I could buy my own NGK plugs and have them installed. Motor is a 2009 Honda BF135AKX. Dealer siad that was okay, but said I HAD to buy the NGK plugs that come in Honda's redbox with a Honda label on them. Here's a direct quote to be accurate:

FYI ~ there are differences between the OEM marked parts versus the aftermarket components and while not always, sometimes even parts like spark plugs from NGK can have the same base part number but be slightly different. The OEM marked Honda Marine spark plugs are NGK's but come in a red packaging marked for use in Honda Marine engines. These plugs are manufactured specifically for Honda and are usually not available anywhere except through Honda Marine or their dealers. These plugs typically have a special non corrosive marine grade coating added to help combat oxidation issues, etc... If the plugs you are purchasing are in the Honda red box then they are for the marine grade engine, if they are in the standard yellow NGK box then they are a general service plug and probably not the marine grade plug Honda designed for your engine. They will work and have the proper threads, length and heat range, etc... They will run the engine and to my knowledge will not harm anything, they simply may not last as long, etc... This was not as big an issue with the older two stroke engines as the spark plugs were intended to be replaced every season, due to the carbon and oil ash residue left during the combustion process, etc... The four strokes burn cleaner and the plugs can last several years without any issues. In our area, we typically like to replace the plugs on a four stroke after three years of service. the average unit we service typically has around fifty hours of run time per season on the engine.

So I called NGK Tech Support and asked them what the difference was between the $23 Red boxed Honda labeled 9807B-5617W S/PLG (IZFR6K11) (NGK IZFR6K11) plug the owners manual recommended, and dealer said had to be in the red box, COMPARED TO: the same NGK IZFR6K11 plug in the yellow box I could buy at Advanced Auto for $9.99 each. The factory rep at NGK said the plug is exactly the same plug, and the coating the guy at the boat dealership is talking about is the process used on all that model number of plugs. The only difference is the one that goes thru Honda, gets Honda's 2 year replacement warranty from Honda. (FYI Honda warranty on "Honda" NGK plugs is only good for 2 years and only if the plug was the original one put in the engine. So if you are replacing plugs, the 2 year Honda warranty does you no good). The Yellow boxed NGK plug available thru car parts stores only has whatever warranty the parts store gi es you. At Advanced, that's 90 days. ( 4 Honda plugs at $23 each = $92, vs same plug at Advanced Auto = $39.96)

The Honda boxed plug costs more because if it fails under Honda's warranty, Honda has to pay the dealer labor and the cost of the part to honor their warranty. There's also a cost to Honda for the redbox packaging and for applying a Honda label as shown below. In the case of the auto parts store plug, the parts store only warrants the plug, and the customer has to install it himself. So Honda adds the price of a possible warranty replacement and its expected labor costs to the cost of the plug they sell.

So when you go to buy plugs for an OEM engine, pull the plugs spec up and compare it to what the plug will cost at a parts store vs dealer who says "it has to be an OEM PACKAGED plug".