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