car oil in boat

[rob711]

i have a 2005 4 stroke 115hp merc o/b..i picked up the oil filter and gear oil the other day at the local boat store..the manual says to use 10w 30 motor oil..they only had 5w 30..or something elese that was not 10w-30. the guy said that every one uses that and i'll be ok..i'd rather use whats recomended..any problem using a good 10w-30 automotive oil...i know it won't say marine on the label but is there any other difference. thanks
rob

 

[Cricket Too]

Re: car oil in boat

If your gonna use automotive oil, then there's not gonna be much difference between 5w-30 and 10w-30, just it's fluidity when cold, they are both 30 weight oils when hot. I prefer the 5w in my truck, it gets moving a bit faster than the 10w, especially in the cold.

I believe the marine 4 stroke oil is enhanced to not be as sensitive to the water intrusion that is normal in 4 strokes, and may have some other enhancements to it, to put up with the constant strain of a marine engine.

bobistheoilguy.com is a great site to find out about all types of oils and fluids.

 

[Chris1956]

Re: car oil in boat

Rob, You need to consult your owners manual to se if the auto oil is recommended. On my Sterndrive, multivis auto oil (i.e 5W-30, 10W30) was not recommended, but straight weight SAE-30 oil was recommended. I suspect your outboard will need a special motor oil, due to its duty cycle.

 

[wbeaton]

Re: car oil in boat

I don't know about outboards, but lots of small 4 stroke motors call for SAE 30 in summer and 5W30 in winter. I run 5W30 in all of our small 4 strokes at work since we use them all year long and the guys can't be trusted to change the oil. I'd probably rather run straight weight in an outboard since it won't be running in freezing temps, but I wouldn't be concerned about running 5W30 either. IMO

 

[JB]

Re: car oil in boat

I used 5W30 Mobil 1 in my Suzi on recommendation of the dealer.

 

[whywhyzed]

Re: car oil in boat

they are both 30 weight oils when hot

that's sort of right, more right when the oil is fresh, but also sorta backwards.....

5W30 is made from a 5 weight base stock
10W30 is made from 10 weight base stock

The additives (thickeners) cause the oil to "act" thicker when they get hot, but towards the end of their use, the additives wear out and you can be left with mostly base stock.

For that reason - I would go to another store and get some 10W30. Also, there's more additives in 5W30. I prefer less complicated oil if it's possible because at the end of the season it tends to more closely resemble it's composition when it went in

 

[Cricket Too]

Re: car oil in boat

kjd.....Interesting, I always thought it was the opposite. I thought they were 30 weight base stocks and the additives are what gave them their winter weight, based on temperature. Thanks for the info.

 

[jeeperman]

Re: car oil in boat

kjdkjd,
what about the difference in oils when the containers have the exact same weights and codes (API) etc. and the only difference is one has the word "marine" and the other does not?

Oh and the "marine" labeled oil is $2.00 a quart more than the bottle without the word "marine" on it?

Such as GL-5 gear oil.
Both are GL-5 and the same weight stuff.

 

[rob711]

Re: car oil in boat

thats how i feel jeeper...but since its my first new motor ever i think i'm going to bend over and by the marine oil!!

 

[Cricket Too]

Re: car oil in boat

Keep in mind that your 4 stroke outboard isn't running at the same temperature as the one in your car, it runs a lot cooler, and obviously the oil doesn't get as hot either, so it tends not burn off the moisture that accumulates in the oil.

That's why people sometimes check their oil and there is more than they ever put in, there are extra things accumulating in the oil that don't burn off. There's a whole post somewhere here called, 4 stroke "making" oil, or something like that. Marine oils are supposed to have enhancements that make them less vulnerable to this, same as in marine grade gear oils, they tend to be less vulnerable to water intrusion and foaming.

Also you don't run your car at a constant 5,000 RPM under a heavy load, marine oils are supposed to be abe to stand up to this better. I don't know for sure if they are actually different than automotive oils, but for the amount you change the oil in your ourboard, what's an extra $10 just in case they are better?

 

[jeeperman]

Re: car oil in boat

So howcome the container of oil does not have any codes or standards numbers that are different then other oils?

i.e. the only difference is the word "marine" on the label.

Should not the standards codes be different if there are different ingrediants in them?

 

[jeeperman]

Re: car oil in boat

It smacks of paying more for tires just because they are going on a Cadillac.

 

[skeat]

Re: car oil in boat

Oils labeled marine are suppose to have different additives and corrosion inhibitors in them and I suppose other more technical stuff that I'm not up on. I try to use Pennzoil HD Marine 30W. My boat is my baby so she gets spoiled

 

[Frank Acampora]

Re: car oil in boat

I used to think that there was no difference in oils (for example lower unit gear lube) and the oil companies were trying to make a little more money off me--and don't get me wrong, any company would try to sell its products at a higher price if it could. Example: Catalog companies--including Victoria's Secret-- have different pricing structures for different areas of the country. If you call in an order it is wise to ask "Is this the lowest catalog price?" otherwise you will be charged higher for the same item sold elsewhere. If you ask, they are required to give you the lower price. --Hint given to me by my daughter. She did it regularly.

But logically, the boat market is minuscule compared to the auto market and Currently, I don't think the oil companies are making their billions of profit off us with special 4 cycle oil. In this case I tend to believe that there is really a difference that makes the oil cost more. However, If someone were to come up with documented proof rather than hearsay, then my opinion would change. Maybe if couple of you wrote to Consumer Research mag they might investigate. And if I owned a 4 cycle outboard, I would research the oil because I am cheap and always willing to save a couple of bucks--just on principal.
I don't live in a dreamworld.

 

[TheOilDoc]

Re: car oil in boat

An API SE, SF, SG, SH, or SJ oil of SAE viscosity 10W-30 or 10W-40 is recommended by the manufacturer, and that is what you should use.

I would recommend the latest API classification in a 10W-30 FC-W.​

 

[rob711]

Re: car oil in boat

i did'nt realize this was still going on...i put 25w-40 in it from mercury..the owners manual says its ok to use at temps above 40 degrees..other wise it wanted 10w-30.thanks all..

 

[Chris1956]

Re: car oil in boat

Rob, Did Mercury really recommend 10W-30 motor oil? Was it their brand, or was the FC-W designation required by this oil?

 

[Cricket Too]

Re: car oil in boat

I don't think I'd use any multi viscosity automotive oil in my 4 stroke, since it may not get to a high enough temperature to actually be a 30 weight oil when it needs to be. I'd hate to be running at 5500 RPM with my engine at 140 degrees or so and have my 10w30 only be acting like a 15 or 20 weight oil under a heavy load. I would assume marine oils would get to their highest viscosity at lower temps than automotive oils, like I said....assume.

Just my opinion. If it costs an extra $10, then you just paid $10 for peace of mind on your $15,000 engine. Seems like a bargain to me.

 

[Bondo]

Re: car oil in boat

Oh Boy,.......................Another "Oil" thread...................

I'm still running Mobil 1, 15W-50 the my 4.3LX,+ Mobil 1, 75W-90 in my Alpha 1 drive.......
And,.........
ATF in my Trim Pump,+ P/Steering........................

 

[rob711]

Re: car oil in boat

chris...yeah according to the shop manual for the motor 10w-30 was for all temps and 25w-40 for above 40 degrees..and it also stated some thing to the effect that if these marine oils were not availble to use a high quality automotive style oil..i'm at work right now but if i get motivated enough tomorow i'll try to scan the page then post it....