Mercury Four Stroke 10w30 / 42 Hours / 2019 Mercury Four Stroke 200 3.4L V6

[Jstew]

Considering switching to Rotella T5 10w30 when my warranty is up as the engine is spec’d for 10w30.

The Mercury oil is straight conventional, and is a “catalyst compatible” oil, both of which are reasons I would like to get away from it. It is hard to find an oil with the marine NMMA approval that is not catalyst compatible these days, and this motor does not have a cat.

I found it interesting that the universal averages are based on 50 hours. Manufacturer OCI interval is 100 hours, but 42 was all I could put on it last season. I’m glad I did a UOA, as I would not have wanted to run much longer with the fuel dilution.

Regarding the fuel dilution, I was a little surprised - I don’t think I idle extensively, just no wake zones where I try to come off idle to around 900 rpm to increase water and oil pressure.

 

[Rygrego]

I have 2018 200 hp Mercury also and have run Rotella T6 15w40 since the first oil change. There is nothing special about the marine oil besides the marine rating. You don't need to worry about catalytic converter ratings as you don't have any. Don't let anyone tell you your warranty will not be honored for using this oil (it's not true). Rotella has been used in marine applications for many years by people who know boats.

 

[FZ1]

Wear looks good. I think that Merc oil is a syn blend. Maybe just change it 1x per year when you change the lower unit oil.

 

[Jstew]

Wear looks good. I think that Merc oil is a syn blend. Maybe just change it 1x per year when you change the lower unit oil.

This oil was conventional - “red label” bottle. Mercury does offer a syn blend, it has a white label and states syn blend on the bottle.

 

[FZ1]

Jmo I think I would not change up too much. The wear looks good. I would try the syn blend. Quicksilver syn blend is also a good blended marine oil in 10w-30 available at Academy or WM.

 

[sunruh]

let me just say this....at looking at uoa reports for almost 18 years now..i dont remember seeing a flash ever as low as 310
not sure i remember one under 350.....of my own 94 reports i have 2 with a flash of 355.
that does NOT stack up to a 3.3% fuel....nope there is a L O T more fuel in there than 3.3%
im kinda shocked it even shows at the top of the 20wt chart on susvis because of the fuel
ive seen 2.0 and 2.5% fuel show much higher flash

i just hope you are not using ethanol whiskey fuel ... all that alky soaking up water to do damage...NOT GOOD

 

[Bonz]

My thought is look at the SusVis as a positive giving the fact that the flashpoint was so low. I consider those two reading more reliable from Blackstone than showing 3.3% fuel. They don't even have to do fuel dilution (regardless if it's accurate or not) as the flashpoint tells all in my opinion

 

[sunruh]

but then that would mean the susvis would be suspect of being reported way to high for what it actually is.
at least 1 of those 3 numbers (flash, susvis, fuel dilution) is NOT correct.
a susvis of upper 20wt could be correct....if it started as a really thick 30wt and the 3.3% (if true) of fuel brings it down (meaning the flash is way low for what it should be).
there is a LOT of ifs/buts found in those 3 values in my eyes.

so...once again...a stoner report that does not make any sense.