Best Crank Case Oil

[jeepnsam]

Now that I have the spark plug mystery all sorted out..let's talk "best crank case oil" for Marine engines. (whole different ball game from car engines)

1995 Searay 180
Merc 5.0 Alpha I Gen II
WOT = 4200 to 4600 rpm
Temp Gage = 170 to 175 degrees

San Diego, Nevada and Arizona boating in 95 to 120 degree weather and my boating season from April to Sept. Most boating done between June and August when it's 100 degrees and above.

Owners Manual Says:

* Quick Silver 4 Cycle Marine Oil
* SAE 30W

I'm thinking 100 degree weather, WOT at 4200 to 4000 rpm most of the day
would give me 10w40 Marine Oil as the better oil for my environment.

What do the "experienced" boaters suggest??

Thanks,
Sam "The Newbie" Brown

 

[7228sedan]

Re: Best Crank Case Oil

What kind of oil pressure are you getting now? I'd stay away from the multi viscosity stuff (10W40) etc. The supposed benefit of the multi viscosity oil is that it has the properties of both a 10 weight & a 40 weight depending upon the operating conditions. In a marine engine, there's no real reason to run the multi viscosity oil unless you are in a cold climate. The 10W40 stays "thin" for a cold start up in cold weather. When you'll be cranking the motor; it'd probably be close to 100 degrees in the engine compartment before the motor even starts. Stick with the 30 weight if your oil pressure is good at temperature. If it seems low, go up to the 40 weight. I run Rotella 30weight in my 454 here in NJ. I maintain 40 PSI at temperature all day long. I'd like it to be a bit higher, but with over 1000 hours on her I can't expect much more

 

[Philster]

Re: Best Crank Case Oil

Factory manual says what? Yeah, there ya go.

Or Mobile One to make a point.

 

[180shabah]

Re: Best Crank Case Oil

Is there something wrong with the 25W40 that the manufacturer recomends???

 

[HT32BSX115]

Re: Best Crank Case Oil

Sheesh, here we go again!