Genuine Mercruiser oil - or not?

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You'll have to forgive me on this one - I have zero experience with marine engines. This is a new Mercruiser which was purchased by a neighbor. 4-stroke I/O and looks a little like an outboard motor with the lid off. Well, sorta. Pretty sure it's a V-6. He says that the Genuine Mercruiser motor oil is $40 a gallon and wanted to know if there was an alternative. Heck, I don't know.

Any thoughts on this?

Thanks.
 
HDEO oil works well for most any use.
Stick with the recommended weights.
Merc doesn't care much for full synthetic oil, so bare that in mind.
Rotella is reasonably priced, and the synthetic (blue jug) is considered very good stuff; though the conventional (white jug) maybe just the ticket for your neighbor's engine.
 
You generally don't need a synthetic in a marine engine. As previously stated, Mercury seems to agree. The bigger issues are fuel and water dilution/contamination and shear down.

If it's an I/O, then a conventional HDEO in a straight weight or 15w-40 usually works well, even in the newer engines. If it must be a synthetic at palatable cost, then M1 15w-50 may still be a good alternative. I'm still leery of running a 5w-40 HDEO synthetic in a marine engine.

If it's still under warranty, be sure to stay within the recommended viscosity ranges so there isn't a claim problem. I haven't looked at their warranty booklet lately, but Mercury may also now require FC-W compliant oils. I think the FC-W is not that big a deal, but I'm not the one deciding warranty claims.

If it's a new four stroke outboard, all bets are off, and he should stick with the manufacturer's recommendations.
 
right from the Sea Horse's mouth
read the last line. says it all.
$20k boat and $6 propulsion unit, don't get cheap on the oil.

http://www.mercurymarine.com/serviceandwarranty/mercruiserfaqs/fueloil.php
What type of oil should I use? Can I use synthetic oil?

Engine Oil

To help obtain optimum engine performance and to provide maximum protection, we strongly recommend the use of the following oils listed in the order of recommendation:

1. MerCruiser / Quicksilver Synthetic Blend, NMMA FC-W rated, 4 cycle oil.
2. MerCruiser / Quicksilver 25W40 NMMA FC-W rated oil.
3. A NMMA FC-W rated oil.
4. MerCruiser / Quicksilver 4-cycle 25W40, non FC-W rated oil.
5. A good grade straight weight detergent automotive oil per the operating chart below.

NOTE: The use of non-detergent oils, multi-viscosity oils (other than as specified), non-FC-W rated synthetic oils, low quality oils or oils that contain solid additives are specifically not recommended.

http://www.nmma.org/certification/programs/oils/registeredoil.asp?y=FC-W2008
 
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Guys,remember, The "Sea horse" is Johnson...
But really, don't go low in viscosity with the marine blocks.
 
15W-40 Rotella or Pennzoil HDEO will serve you well. That's all I've ever used for ENGINE oil on my 3.0 Mercruiser. Now the outdrives, that's a different beast. If you have an Alpha drive, you can use the dino version, the Premium. For Bravo's and above, you need High Output.
 
Shop for the merc quicksilver 25w40. You can find it cheaper off season which means now. Most boaters change oil in the Fall. Check West Marine as I have bought the 25w40 there for $11-14/gal. Sometimes they will have a $10 off coupon so my 3 gallons will cost $32. Pennzoil Marine 15w40 is good as well and some Walmarts carry it. My local WM carries the Merc 25w40 for $4.50/qt regular price.
 
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I get those two things messed up. The alpha can easily handle the dino version, which I thought was the premium, but your right. That synthetic stuff is expensive and STINKS. I use to use the synthetic stuff on my Alpha Gen. II setup, but read a Mercruiser BB that said for the 3.0, the dino stuff is fine.
 
Originally Posted By: PT1
Shop for the merc quicksilver 25w40. You can find it cheaper off season which means now. Most boaters change oil in the Fall. Check West Marine as I have bought the 25w40 there for $11-14/gal. Sometimes they will have a $10 off coupon so my 3 gallons will cost $32. Pennzoil Marine 15w40 is good as well and some Walmarts carry it. My local WM carries the Merc 25w40 for $4.50/qt regular price.


FWIW the merc 25w40 is now $19/gallon at West Marine
shocked2.gif
 
Local Wal-mart has been carrying Quicksilver oils.
Not sure about that specific weight, but they have several
different grades/levels of those oils.
 
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