I'm going against the grain and saying just stay with 25w40 under warranty. Mercury has outstanding R&D and blends some of the best marine oils on the market. Quicksilver 25w40 gallon jugs can be had for less than $25. Out of warranty, do whatever knocks your socks off.
2019 200 hp Mercury Outboard Oil
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Originally Posted by Rygrego
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.
Wouldn't the water temp of the lake be more concerning than the ambient air temperature?
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.
Wouldn't the water temp of the lake be more concerning than the ambient air temperature?
Originally Posted by billt460
Originally Posted by Rygrego
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.
Wouldn't the water temp of the lake be more concerning than the ambient air temperature?
not for the first 30secs (roughly) as the air temp would set the water temp in the block because no fluid has been pumped through it. ie the block is at ambient temp.
however, once that water pump starts pulling in fresh water...then that temp does indeed change..but again however, the oil is already moving and doesnt really come into play on startup.
a boat motor (both inboard and outboard that pull from the body of water they are on) go through this very fast temp swing on the coolant in the first 1min. and a hot body of water could be more than the ambient...so could be both ways.
and realize that some inboards pump the water throught the exhaust manifolds to get the water temp warmer to begin with to prevent to radical of a temp diff and prevent block/head cracking.
also realize that almost ever single outboard just idles for 3-5mins as its taken off the trailer and moved over to the dock and then the truck is put away and finally out of the wake zone the throttle is finally opened up. you dont rev a boat motor right after start up...there is almost no place that its possible to do so. so in the end...the motor gets up to a decent temp before any throttle is applied. AND you are not putting a boat on a lake when its frozen...so its not really that cold anyway (ie when 20w weights would be too thick for the ambient).
in a nutshell...a non issue
Originally Posted by Rygrego
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.
Wouldn't the water temp of the lake be more concerning than the ambient air temperature?
not for the first 30secs (roughly) as the air temp would set the water temp in the block because no fluid has been pumped through it. ie the block is at ambient temp.
however, once that water pump starts pulling in fresh water...then that temp does indeed change..but again however, the oil is already moving and doesnt really come into play on startup.
a boat motor (both inboard and outboard that pull from the body of water they are on) go through this very fast temp swing on the coolant in the first 1min. and a hot body of water could be more than the ambient...so could be both ways.
and realize that some inboards pump the water throught the exhaust manifolds to get the water temp warmer to begin with to prevent to radical of a temp diff and prevent block/head cracking.
also realize that almost ever single outboard just idles for 3-5mins as its taken off the trailer and moved over to the dock and then the truck is put away and finally out of the wake zone the throttle is finally opened up. you dont rev a boat motor right after start up...there is almost no place that its possible to do so. so in the end...the motor gets up to a decent temp before any throttle is applied. AND you are not putting a boat on a lake when its frozen...so its not really that cold anyway (ie when 20w weights would be too thick for the ambient).
in a nutshell...a non issue
Mercury made a synthetic 20w40 and made that the recommendation for all motors about 5 years ago. Then they stopped selling it and made the recommendation 25w40 semi for all motors.
I think it comes down to Merc only recommending what they private label and sell.
I think it comes down to Merc only recommending what they private label and sell.
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Merc does not like viscosity modifiers … and considering many don't run motors in extreme cold they can use the tight spread Merc or QS oil
T6 has a 12 NOACK last I heard … and more VM … twice what Mystik marine oils have. I'd just as soon use Delo or Delvac 15w40 for way less if you don't need 5w
Also comes down to how often you change the oil. For me it's just yearly but commercial crabbers etc like the truck oil since they change often.
T6 has a 12 NOACK last I heard … and more VM … twice what Mystik marine oils have. I'd just as soon use Delo or Delvac 15w40 for way less if you don't need 5w
Also comes down to how often you change the oil. For me it's just yearly but commercial crabbers etc like the truck oil since they change often.
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