2019 200 hp Mercury Outboard Oil

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Recently purchased a new tritoon with a 200 hp Mercury Four Stroke. My question is why does Mercury not recommend synthetic oils in their outboards? The manual only recommends mineral or semi synthetic 10w30 or 25w40. I am at my 20 hour service and would like to run Rotella T6 15w40. Boat is operated only in Arizona in 100 to 115 degree weather. Water temp stays pretty consistent at 140 degrees, which I understand is normal.
 
Recommend oil is NMMA certified.
Mercury always recommends a narrow spread viscosity to avoid VM. Just don't need synthetic for what's basically close to a mono in Merc or Quicksilver.

If you plan to run 15w40 … what does T6 offer over T4, Delo, or Delvac in 15w40?
 
I stopped using anything other than synthetics years ago while I was an over the road auto transporter for new car manufacturers. Our fleet was over 400+ rigs and in about 2001 we became a test fleet for Mobil 1 Delvac. We were running our oil then up to 65,000 miles between changes with filter changes and oil samples at 12,000 miles We had only one oil related failure in 10 years and that sold me. I have been running Rotella T6 in my motorcycles, Jeep and trucks with zero problems and extremely clean internals. I would run Delvac 1 except for its cost. Synthetics create far less carbon build up from my experience. But back to my original question, why does Mercury not recommend any synthetics for their outboards? Just about any diesel oil will exceed the NMMA specs, including foaming.
 
In the USA, what is marketed as synthetic is just a group 3+ oil, very similar to normal oil. so I think you could use with no worries. Maybe the regular oil is better at fighting corrosion when it is not run for 2 or 3 weeks at a time. Their monograde oil is fine, almost no one goes boating when it is below freezing.

Rod
 
heard that before … guess NMMA should not exist just like similar organizations …
 
I am not ignorant of oil groups and know exactly what group 3 is. But a hydrocracked group 3 is far superior to any group 2. I didn't start this thread to get into this blackhole, I just was wondering why the Mercury manufacturer does not recommend synthetic oil when it is better in every way.
 
Actually Delvac Super is made from the new GII+ which is also HC … as GI gets phased out … GII is getting better.

Other than your belief system wrt synthetic … what advantages does T6 in 15w40 have over premium conventional 15w40 HDEO or a Chevron Delo semi ? (DNewton has posted dozens of counters against this thought)

Now, think you meant to plug for Delvac 1. Yes, last I knew in 5w40 it had 30% PAO and other base stock … so Mobil could minimize VM. But, with 15w40 that's inherently easy in any formula … so closer to what Mercury is looking for.

Last comment, I don't doubt HDEO is versatile … but it was not tested and approved for that motor …
 
There is a reason why you do not see NMMA oils for marine diesel engines.

Pick any category of oil spec and the diesel engine manufacturers spec completely blows away NMMA. To have an NMMA diesel oil would be redundant and a lower bar.

NMMA cert just means that an oil has met a certain set of standards. It does not mean that an oil is loaded with all sort of magic that a traditional oil does not.

My guess is that Mercury prefers semis and dino because of the information that goes around that Dino's and semis tend to remain coated on engine parts over a longer period of time when not run.
 
What you did not post (and you know it) is that NMMA does WOT tests in 4S motor ... checks the oil ...and tears down the power head for inspection

Wonder why the HDEO's don't just test at NMMA facilities and then rebadge the bottle

It would surely sell for more than 12/gallon ... missed opportunity to double price?

Here is one of the NMMA lube makers ... specs on the link
Exaggerating aside... it has good specs
(Noack etc) that T magic does not blow away

https://www.mystiklubes.com/do/product/663095002
 
Originally Posted by Rygrego
Recently purchased a new tritoon with a 200 hp Mercury Four Stroke. My question is why does Mercury not recommend synthetic oils in their outboards? The manual only recommends mineral or semi synthetic 10w30 or 25w40. I am at my 20 hour service and would like to run Rotella T6 15w40. Boat is operated only in Arizona in 100 to 115 degree weather. Water temp stays pretty consistent at 140 degrees, which I understand is normal.


I don't believe Merc sells a full synthetic oil, only a semi unless one is available for inboards?

I have no idea if this is true or not, but my selling marina, where I purchased my boat, told me a couple years ago that Merc was now recommending a semi syn for my 90 HP 4 stroke?
I don't necessarily follow boating forums but I don't recall hearing anything about this new requirement from anywhere. My gut tells me, but could be wrong, that they were just up selling me so they could charge me an extra $60 for my oil change.
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Originally Posted by 4WD
What you did not post (and you know it) is that NMMA does WOT tests in 4S motor ... checks the oil ...and tears down the power head for inspection

Wonder why the HDEO's don't just test at NMMA facilities and then rebadge the bottle

It would surely sell for more than 12/gallon ... missed opportunity to double price?

Here is one of the NMMA lube makers ... specs on the link
Exaggerating aside... it has good specs
(Noack etc) that T magic does not blow away

https://www.mystiklubes.com/do/product/663095002


That would make up a very small portion of the many types of testing and certs that an HDEO has to meet for the diesel manufacturers.

The HDEO manufacturers don't test and rebadge because:

A: Many NMMA oils have to be catalyst compatible. Some companies are no longer even making a non-catalyst oil. Most HDEO is not marine catalyst compatible.

B: The viscosity specs mostly don't match. Nobody makes a popular 25W-40 or 10W40 HDEO.

C: They generally try to duplicate the OEM formula as closely as possible so as not to appear as a goofy substitute.

D: Some manufacturers like Volvo-Penta literally spec a 15W-40 diesel rated oil as the OEM spec oil for a gasoline engine

E: The diesel manufacturers are just not interested in an immensely transparent marketing scheme.

The part that you forgot to post is that many marine engine manufacturers spec an automotive non-NMMA oil for their gasoline marine engines.

https://www.indmar.com/engines/

Notice which spec Indmar goes by for all of its engines? That's right. API SN. No mention or usage of NMMA spec at all.

We can rehash this all day long, but the fact that straight up 15W-40 HDEO and OTS automotive oil has pushed out so much of the NMMA oils for gasoline marine engine oil is solid evidence that NMMA is about as good as feet on a beluga whale.

We could also get into the NMMA's hilarious adventures in destroying thousands of 2-stroke engines with their arbitrary specifications, to the point that almost every marine engine manufacturer ran away from them and formulates their own 2-stroke engine oils to this very day.
 
I don't have an answer to the no full synth situation. I do have a question......why would one drop $50K+ on a rig and NOT follow the engine manufacturer's oil recommendations? It doesn't have to be Mercury/Quicksilver brand name, Super Tech has 25W40 NMMA syn blend outboard oil for $14.00 a gallon. I would pay the money for a Merc oil filter though.

Edit: I just looked up the recommended oil for the standard 3.4l V-6 200 and it shows only one NMMA FCW 10W30 . See for yourself:

https://embed.widencdn.net/pdf/plus...V-6_V-8_Compare-Chart-200hp.pdf?u=orhjei
 
Last edited:
Originally Posted by RTexasF
I don't have an answer to the no full synth situation. I do have a question......why would one drop $50K+ on a rig and NOT follow the engine manufacturer's oil recommendations? It doesn't have to be Mercury/Quicksilver brand name, Super Tech has 25W40 NMMA syn blend outboard oil for $14.00 a gallon. I would pay the money for a Merc oil filter though.

Edit: I just looked up the recommended oil for the standard 3.4l V-6 200 and it shows only one NMMA FCW 10W30 . See for yourself:

https://embed.widencdn.net/pdf/plus...V-6_V-8_Compare-Chart-200hp.pdf?u=orhjei


I didn't know Super Tech also had one and while searching a little further, I see Star Brite also has one.

http://www.starbrite.com/item/premium-synthetic-blend-4-stroke-outboard-oil

Maybe I am being silly, but personally, and since I have had good luck using Merc oils, I will stick with either Quick Silver or Merc oils going forward.
 
Thank you, but my engine placard and manual lists 10w30 or 25w40. With the high ambient temps of Arizona I always opt to higher viscosity.
 
Lots of (high hour) fishermen use truck oils … personally I'd use certified oil under warranty but I also land on that side during debates over vehicles (and I have certainly used HDEO in gassers outside of warranty)

I have yet to see the magic others see in T6 when it costs more yet has a higher Noack compared to Delo and Delvac

It's a big been there, done that, passes it on … not saying it's not working but plenty other lubes do too including cheaper Shell products
 
I've said it before, there is nothing "wrong" with an NMMA approved oil. It's a good, safe bet. Especially for your typical boat owner who just doesn't know any better.

I've seen a lot of jugs of 5W-20 on V8 cruisers. Spooky. I get what NMMA is trying to accomplish, and most people would probably be better off putting NMMA blinders on their eyes. But there really isn't a whole heck of a lot going on there, other than some much needed gatekeeping for the masses.
 
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