I’m a hands on kind of guy, change my truck oil, rotate tires, etc. but I’ve never changed my own boat oil. I have an 07 Merc 115 efi fourstroke and from the mercury website it looks as though I should just be using any 10w-30. Is this right? Should I be looking for a marine type like merc’s brand or will any Quaker State, Pennzoil work.
That is a good question. I have been unable to find inexpensive 4-stroke outboard oil at Wally World,Fleet Farm etc.. So I go to the marine dealers and pay $7 or $8/qt. Then in the fall when I drain it, the oil looks as clean as the day it went in. I know it’s only $25-$30/year but why can’t I use the $2/ qt. auto engine oil at the discount stores? Do I realy need to change annually?
I’ve been running Mobil 1 10-30 in my 40hp Merc for 5 years and I run that motor ALOT. No problems.
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I’ve been running Mobil 1 10-30 in my 40hp Merc for 5 years and I run that motor ALOT. No problems.
Ditto. Mobile 1. Good stuff!
-J.
I prefer and use marine grade 10w30.
That just me tho.
Look in the manual and as long as you use oil that has the same properties you should be fine. I would stick with a quality synthetic oil, such as Mobile 1. 
Fleet Farm has Shipmate and Mystik outboard 10w-30 oil on sale for 3-4 bucks until the 15th. 
Back a year or two ago Bass and Walleye Boat mag did a 4 stroke oil comparison. They tested all the major outboards oils. If I remember right Mercury oil faired very well as did Mobile 1. Something to remember is that car oils aren’t made to handle sustained high rpm like outboard oils. Nor are they as good at corrosion protection.
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Something to remember is that car oils aren’t made to handle sustained high rpm like outboard oils. Nor are they as good at corrosion protection.
Now that seems like good info. I run synthetic in my Honda kicker. Could the “synthetic” be the key here. 
I really don’t know. But I run auto Castrol (non-synth) in my motor cycle at sustained RPM’s and no problems there. What changes? 
As long as the oil ratings are the same on the bottle of oil what would it matter. They should have the same oiling properties. I ran Mobile 1 or Amsoil full synthetic in my kickers with no issues.
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