4 stroke marine oil

[Rizzo]

Sad day...winterized the boat today. Had a tough time finding 10w30 4 stroke marine oil BUT I saw tons of 25W40 4 stroke marine oil. I had never noticed this type of oil before. Is this what is being recommended now for 4 stroke engine oil? I did find eventually some 10w30 and bought it but was surprised how much of the other I was seeing (maybe there was so much because nobody buys it!) My engine is a 90 hp Yamaha 4 stroke from 2013 if that makes any difference.

[misfish]

Oils oil.is it not?  Melt some lard like the old days before you and I, and pour it in. I know a deal on seal fat. Super slick.lol

29 minutes ago, Rizzo said:

Sad day...winterized the boat today.

And yet, so south of Barrie. How can that be?

 

It had to come Rog.

 

I am sitting here smelling smoked brisket on ye way. Steel head sides to follow.

Can not say,I feel yer pain,,,,,,,,,,,

Wait, I do,,,,,,,,,,,,,,,,,,,,,,

 

Cheers bud

[DRIFTER_016]

25W40 is what Mercury calls for their 4 stokes.

 

[cisco]

Googled it and found in general...

"Mercury Marine says it spent the last five years developing a new line of four-stroke marine oils, featuring three formulas designed specifically for outboard and inboard/sterndrive engines. The two key four-stroke oils in the product line have a 25W-40 viscosity rating, and are produced with either a semi-synthetic or straight mineral-base stock formula. The third oil in the lineup is a 10W-30 mineral-base stock oil intended for use in rope-start outboards because it’s easier to pull over in a cold engine… call it duck hunter’s oil."

Here due to a generally colder climate the thinner oil is recommended. Since you musky hunt in colder weather at times I'd stay with the 10W30 thinner oil. 

[Fisherman]

I've been using the Amsoil 10W30 for over 25 years,  it meets all the specs. 

[LeXXington]

I have a 2008 - 90 merc and It has a label printed right on it for 25-40.   On the 9.9 yam it says 10-30.. 

[DRIFTER_016]

4 hours ago, cisco said:

Here due to a generally colder climate the thinner oil is recommended. Since you musky hunt in colder weather at times I'd stay with the 10W30 thinner oil. 

My local Merc dealer told me the same so I run 10W30 Mobil 1 in my motor.

[Rizzo]

Guess I never noticed the 25w40 because it was easy to find the 10w30...went straight for that. This time when the first two shops only had the 25w40 it got me wondering. Luckily third shop was the ticket

[wkrp]

17 hours ago, Fisherman said:

I've been using the Amsoil 10W30 for over 25 years,  it meets all the specs. 

x2 on that and my merc 50 purrs like a kitten.

[bigbuck]

Any good quality synthetic motor oil that meets the specs will do the job just fine. I use Motomaster synthetic gear oil in my lower unit, better than the semi synthetic stuff marinas use. I run whatever 20w50 dyno oil I find on special in my i/o, the key being yearly oil changes. 

[captpierre]

So my marine Yamaha 10w30 jug says it has additives in it specifically designed for marine engines exposed to high moisture environments. Are you guys using automotive oils?

[Fisherman]

1 hour ago, captpierre said:

So my marine Yamaha 10w30 jug says it has additives in it specifically designed for marine engines exposed to high moisture environments. Are you guys using automotive oils?

No, we use this: https://www.amsoil.com/shop/by-product/motor-oil/marine/10w-30-synthetic-formula-4-stroke-marine-oil/?code=WCTQT-EA