Oil for Tohatsu 20 HP outboard

[reynoldsmachine.hr@gmail.]

Owners manual says that you can not run synthetic oil in this engine. Calls for 10w40 semi synthetic. Manual says synthetic oil will cause gasoline blow by on rings.
Is this accurate or some marketing hype. For those not familiar this is the same power head in the 20 HP mercury. Tohatsu builds Mercury's smaller engines.

 

[JavierH19]

Pure nonsense. Pretty much any will do being honest. 15w-40 like delo or valvoline from walmart would be my choice.

 

[wings&wheels]

New engine? I would run a few hours or a season on semi then switch to full.

 

[UNC196]

I use full syn marine oil.

 

[reynoldsmachine.hr@gmail.]

New engine? I would run a few hours or a season on semi then switch to full.

It's several years old. Well broken in. My Tohatsu dealer closed so I would have to orderTohatsu oil now.

 

[Japanese]

It's several years old. Well broken in. My Tohatsu dealer closed so I would have to orderTohatsu oil now.

How much was that oil at the dealer? It looks expensive. I found it for about $60 a gallon.

Here are a few online options. I'll probably go with Yamalube which says is mineral/conventional.

Amazon
https://www.amazon.com/s?k=10w-40+marine+oil&crid=4AZGVQHCTCMY&sprefix=10w-40+marine+oil%2Caps%2C156&ref=nb_sb_noss_1

eBay
https://www.ebay.com/sch/i.html?_nkw=10w-40+marine+oil&_trksid=p2553889.m4084.l1313

Walmart
https://www.walmart.com/search?q=10w-40+marine+oil

 

[ripcord]

The Tohatsu manual I found on their site called for API SH, SJ or SL rated oil. Those as specs are so greatly out of date that I wouldn't give it much credit. Modern synthetics will be fine.

 

[reynoldsmachine.hr@gmail.]

How much was that oil at the dealer? It looks expensive. I found it for about $60 a gallon.

Here are a few online options. I'll probably go with Yamalube which says is mineral/conventional.

Amazon
https://www.amazon.com/s?k=10w-40+marine+oil&crid=4AZGVQHCTCMY&sprefix=10w-40+marine+oil%2Caps%2C156&ref=nb_sb_noss_1

eBay
https://www.ebay.com/sch/i.html?_nkw=10w-40+marine+oil&_trksid=p2553889.m4084.l1313

Walmart
https://www.walmart.com/search?q=10w-40+marine+oil

I think I paid dealer about $12 a quart last time I bought it.

 

[reynoldsmachine.hr@gmail.]

The Tohatsu manual I found on their site called for API SH, SJ or SL rated oil. Those as specs are so greatly out of date that I wouldn't give it much credit. Modern synthetics will be fine.

I did some more reading. Tohatsu says the engine runs too cool with synthetic oil and due to it running too cool, it blows gasoline by rings.
Sounds crazy to me.
Same engine with mercury name on it calls for 25w40 conventional, but Mercury does not come out and say you can't run synthetic in it like Tohatsu did.

 

[reynoldsmachine.hr@gmail.]

How much was that oil at the dealer? It looks expensive. I found it for about $60 a gallon.

Here are a few online options. I'll probably go with Yamalube which says is mineral/conventional.

Amazon
https://www.amazon.com/s?k=10w-40+marine+oil&crid=4AZGVQHCTCMY&sprefix=10w-40+marine+oil%2Caps%2C156&ref=nb_sb_noss_1

eBay
https://www.ebay.com/sch/i.html?_nkw=10w-40+marine+oil&_trksid=p2553889.m4084.l1313

Walmart
https://www.walmart.com/search?q=10w-40+marine+oil

The 10w40 lucas was what I was considering using.

 

[Japanese]

The 10w40 lucas was what I was considering using.

In your case, I'll go with Yamalube because it's cheaper when you get a gallon. And also because Lucas is synthetic and you said you look for non-synthetic oils.

The Tohatsu manual I found on their site called for API SH, SJ or SL rated oil. Those as specs are so greatly out of date that I wouldn't give it much credit. Modern synthetics will be fine.

On the back label of Yamalube 10W-40 is written Meets API SJ Requirements.

 

[F150]

I think Penzoil has a Semi at Walmart that should meet all requirements

 

[PontiacHO]

Owners manual says that you can not run synthetic oil in this engine. Calls for 10w40 semi synthetic. Manual says synthetic oil will cause gasoline blow by on rings.
Is this accurate or some marketing hype. For those not familiar this is the same power head in the 20 HP mercury. Tohatsu builds Mercury's smaller engines.

Why not this? This is what Mercury uses.

 

[kschachn]

I did some more reading. Tohatsu says the engine runs too cool with synthetic oil and due to it running too cool, it blows gasoline by rings.
Sounds crazy to me.
Same engine with mercury name on it calls for 25w40 conventional, but Mercury does not come out and say you can't run synthetic in it like Tohatsu did.

Lol.

Please post some pictures of these prohibitions, that would be great to see.

 

[Dodgetracker]

Runs too cool with synthetic??? That’s a dumb statement. Not true at all.