Using car oil

[Johnnyred]

So no definitive answer. Thanks anyway

... I'm guessing you have already used auto oil in your outboard and not just thinking about it. Best of luck to you whichever way you go.

[06 SB]

I think it is very defined. Virtually no single item can void the entire warranty. Although there usually is an exception or two like using the motor in commission of a crime.

Specifically, if automotive oil was used and there is any related failure, the warranty repair will be denied. If your lower unit throws a gear and grenades, I would bet the warranty repair would be covered. This is not hard to comprehend but most want to make it difficult. Use Mercury/Quicksilver oils. They simply work and a few dollars difference is not a large amount in the big picture.

[1ranger487vs]

Was just wondering

[bishoptf]

Was just wondering

Yeah I get it, I will be a contrarian and say that while the motor is under warranty then its probably a safer bet to use what they have called out and to do the maintenance when specified. That way there is no question in regards to warranty if something comes up.

My opinion is that Mercury does does not make the oil and there are probably plenty of non marine oils that would be perfectly fine running in a four stroke outboard but again this is MY OPINION. If you google bitog and read in the oil forums there are lots of threads about marine oil vs say an HDEO oil etc. Once an engine is out of warranty you can decide if it's worth the cost savings or not or find a cheaper FCW rated oil. My mercury manual states not to use Full synthetic oil and a whole bunch of stuff, which really is odd since there are many FCW rated oils that are fully synthetic and I believe Mercury now has full synthetic oil and I assume that it would be allowable now.

Again just my opinion...

[Aj14]

I'm gonna go out on a limb here as I believe he was just trolling and got many of you.
He cant be that stupid.

[yam911]

If one were to take the time to read the Mercury Marine owner's manual it might be seen that Mercury Marine is not mandating that any specific oil be used.

Recommendations only are provided. Recommendations as to what to do and recommendations as what not to do.

There is no mention of a warranty being voided in the event of someone not following Mercury Marine suggestions.

[Zone18]

I am going to have to disagree on that one. The SPECIFIED motor oil called out in the service manual is SPECIFIED...not SUGGESTED. There is a huge difference.
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[GPtimes2]

I am going to have to disagree on that one. The SPECIFIED motor oil called out in the service manual is SPECIFIED...not SUGGESTED. There is a huge difference.
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Maybe the service manual is different from the owner's manual. DIY'ers generally go by the owner's manual. But, if what you posted is from an owner's manual and not a service manual, then they are not all the same. My owner's manual says recommendation, not specification. I can post pics when I am on my other computer if it will help clarify?

[Zone18]

Maybe the service manual is different from the owner's manual. DIY'ers generally go by the owner's manual. But, if what you posted is from an owner's manual and not a service manual, then they are not all the same. My owner's manual says recommendation, not specification. I can post pics when I am on my other computer if it will help clarify?

From my owners manual. Other than the advertising plug for Mercury Quicksilver its telling me the same thing as the service manual.

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[yam911]

I am going to have to disagree on that one. The SPECIFIED motor oil called out in the service manual is SPECIFIED...not SUGGESTED. There is a huge difference.
PXL_20250427_160710527.MP.jpg

That is not consistent with the Mercury Maarine Owner's manuals I have read.

And specifications to me is not the same as a product being specified. But I won't agree that point.

[yam911]

My gut feel is that Mercury Marine is trying to be all things to all users. Trying to help the ones that need the most protections.

But with so many usage patterns I can't see the same applying to everyone.

Mercury Marine can't even begin to know where every motor will be used and how. Their guidance appears to be for the ones that need it the most.

One guy in Costa Rica puts 20 hours a year on his Mercury Marine motor. In a damp saltwater environment. Another guy in Arizona puts 100 hours on his Mercury Marine motor every month. In a bone dry environment.

I dare hazard a guess that the guy in Arizona using automotive oil will have a better motor over time than will the guy in Costa Rica that uses Mercury Marine branded outboard motor rated oil.

I am just glad that we are free to chose and use want we want to use.

[GPtimes2]

From my owners manual. Other than the advertising plug for Mercury Quicksilver its telling me the same thing as the service manual.

PXL_20250427_193247908.MP.jpg

You only posted a partial page. Does the top portion say recommended vs specified?

Here is mine-

[PatriotAW4]

I don't know how this is confusing, both say to use 10w30 FC-W rated oil.

[1ranger487vs]

Aj14. Really

[SilverFox579]

Will that cause it to void the warranty

If Mercury determines the oil used caused the failure and did not meet specified requirements, you bet.

The chart GPtimes posted shows the specified oil -- FC-W or FC-W Cat 10w-30. Automotive oil is not NMMA FC-W certified.

The bold text above the specification chart is clear:

IMPORTANT: Nondetergent oils, multiviscosity oils (other than Mercury or Quicksilver NMMA FC-W certified oil or a major brand NMMA FC-W certified oil), full synthetic oils, low quality oils, and oils that contain solid additives are not recommended)

Run whatever you want in your engine run and pray you never have an oil related failure.

[1ranger487vs]

The question was would it void the warranty not what someone should use. Thought Don would know one way or another. Nothing definitive yet. Lot’s of speculation

[Zone18]

That is not consistent with the Mercury Maarine Owner's manuals I have read.

And specifications to me is not the same as a product being specified. But I won't agree that point.

Well...I posted a picture of my service manual and a picture from my owners manual....so not sure what you have been reading. But to end this conversation....the oil you are supposed to use is clearly stated in both sources of literature. Like others have said....use what you want....I dont care its your money, not mine. This silly play on words you have going is not going to fix or pay for your motor if you have problems.

[MichaelJ3]

The question was would it void the warranty not what someone should use. Thought Don would know one way or another. Nothing definitive yet. Lot’s of speculation

Don has always encouraged us to use the recommended lubes...and I suspect he would reference the FAQ stating that.

My warranty has a few words in it that would really imply Merc expects you to use the recommended lubricants and fuels. Some examples below. See 150 FourStroke Manual from Mercury at this link

"CONDITIONS THAT MUST BE MET IN ORDER TO OBTAIN WARRANTY COVERAGE: Warranty coverage is available only to retail customers that purchase from a Dealer authorized by Mercury Marine to distribute the product in the country in which the sale occurred, and then only after the MercuryMarine specified predelivery inspection process is completed and documented. Warranty coverage becomes available upon proper registration of the product by the authorized dealer. Corrosion prevention devices specified in the Operation and Maintenance Manual must be in use on the boat, and routine maintenance outlined in the Operation and Maintenance Manual must be timely performed (including, without limitation, the replacement of sacrificial anodes, use of specified lubricants, and touch‑up of nicks and scratches) in order to maintain warranty coverage." (Pg 3, Warranty Information Section, emphasis mine)

"15. Use of fuels and lubricants which are not suitable for use with or on the product. Refer to the Maintenance section." (Pg 6, General Exclusions from Warranty Section)

The maintenance section contents has been discussed above, so I won't repeat that.

I think the Magnason-Moss Warranty Act says while you do not have to use the manufacturer's brand oil, you do have to use oil that meets the manufacturer's specifications. In the example case cited above, the warranty incorporates the recommended fuel and oil sections of the maintenance section.

So, I think Merc would have a solid ground to deny warranty coverage if you were not using the recommended oil.

What does your warranty say?

P.S. Don, I know I pasted words from Merc’s copyrighted material; but I’d contend this quoting meets standards of “fair use” for educational and non commercial purposes, is properly cited, and thus is not in violation of forum rules.

[Aj14]

Aj14. Really

If you weren't trolling... I apologize.

[1ranger487vs]

Ok I can see that. So any oil that meets those specifications. Thanks