# 4 stroke oil ???



## Smackdaddy53 (Dec 31, 2012)

Use what’s recommended by the manufacturer.


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## BudT (Jun 29, 2018)

I have seen where full synthetics are not recommended, blends or conventional are recommended. Also what Smack said.


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## mro (Jan 24, 2018)

It appears that "Quicksilver" makes all Mercury's oil for them and have both synthetic blend (w/mineral oil) and have a full synthetic which now is made to meet all Mercury's oil requirements.

I've turned wrenches for awhile and have never cared that much for synthetic oils but about a decade ago a customer required "royal purple" 30wt in his (3) 21 hp air cooled briggs engines. these were operated by employees which were less than attentive if you know what I mean. All motors have less than 2000 hours on them and have only needed regular maintenance.
This was not quite enough evidence to convince me but certainly seems to be a plus for his application.

Think I'll try out the Mercury synthetic blend if I can't find any better convincing info on the full synthetic.

Just a note, not one post what they use in there 4 strokes 
Know two strokes are less expensive and weight less but surprised no one seems to have one.


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## Zika (Aug 6, 2015)

I'm running the same engine and yes Smack, I really like it. 

Have changed oil a couple of times and use the regular Mercury blend, not synthetic, per the owner's manual.

Can't remember the oil weight. The jug is in the boat shed at the coast, but I'll check next week and let you know exact formula.


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## No Bait / Lures Only (Apr 10, 2011)

Smackdaddy53 said:


> Use what’s recommended by the manufacturer.


What smack said!


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## hipshot (Sep 29, 2018)

What's recommended by the engine manufacturer is spec'ed out to the various petroleum companies for bids, and the actual manufacturer of the oil may change every few years. Honda doesn't manufacture oil, they buy it. Yamaha doesn't manufacture oil, they buy it. Suzuki, same. Also Evinrude, Tohatsu, Nissan, Mercury, and all the others. It's formulated to their specifications and bottled under their brand, but they don't manufacture it themselves. I'm not a marine mechanic, but I'd guess that all of the different outboard manufacturers' specs are pretty similar.


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## Steve_Mevers (Feb 8, 2013)

Of course Suzuki is going to recommend you use their 4 stroke oil, but they also list API ratings for oil that can be used in their engines. I have been using Castrol 10-40 oil which meets the API standard for a whole lot less money than Suzuki oil.


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## Marsh Pirate (Sep 15, 2016)

Rotella T-6.


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## mro (Jan 24, 2018)

Marsh Pirate said:


> Rotella T-6.


I've been using shells 15/40 in my 6.2L diesel for the last 350,000 + miles, never got around to trying anything new


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## Marsh Pirate (Sep 15, 2016)

I use Rotella T-6 in my 4-wheeler, zero-turn, push mower, 2 Waverunners, 60 hp Suzuki outboard and F250. You can't use it in anything with a catalytic converter. Bob's the oil guy, is a great place for oil-related information.


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## lemaymiami (Feb 9, 2007)

One thing for everyone to remember about the oils used in marine engines - and it’s their ability to resist breaking down when there’s water present... Oils for cars and trucks might not have that feature. 


I know that BRP specifically uses fully synthetic lube in it’s lower units that are designed to provide the much longer maintenance intervals for E-Tec motors...


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## Smackdaddy53 (Dec 31, 2012)

lemaymiami said:


> One thing for everyone to remember about the oils used in marine engines - and it’s their ability to resist breaking down when there’s water present... Oils for cars and trucks might not have that feature.
> 
> 
> I know that BRP specifically uses fully synthetic lube in it’s lower units that are designed to provide the much longer maintenance intervals for E-Tec motors...


That’s exactly why I made that statement in post #2. I see no reason to deviate from manufacture recommended oil unless there’s a known issue with it.


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## mro (Jan 24, 2018)

Manufacturers recommendation....
copied from the merc manual for 40/50/60 motors

When operating in temperatures above 4 °C (40° F), we encourage
the use of NMMA FC‑W certified synthetic blend 25W‑40 4‑Stroke
Outboard Oil.

looks like my guess was spot on


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## hipshot (Sep 29, 2018)

From my 2019 30hp Honda's manual:

SAE 5W-30 is recommended for general use. 
Honda recommends that you use API service category SG, SH, or SJ oil.
*********************************************************
From my 2016 5hp Tohatsu's manual:

Use only oils that carry the API rating of SF, SG, SH.


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