My boat requires that I use Marine 15-40 oil. Is this something that you can usually pick up at an auto parts store?

walmart bro <BR> <BR>chevron delo 400 <BR> <BR>it is interchangeable with the 15-40 Marine

marine oil is multi weight not multi viscosity like engine oil, boats run cool but work hard, you should use marine oil if you got the money!! if not lose a few hours on engine life and save your cash for gas. If anybody's heard different post a note; I would like to hear it from someone other than a marine oil retailer.

When it comes to discussing motor oils there is so much BS, false information, urban legends and old wive's tales that it is impossible to have a reasonable discussion. <BR> <BR>When you filter out all the crap, there is no such thing as a "marine" motor oil. Some manufacturers put the exact same oil in a bottle with the word "marine" on it but if you go to that manufactures web site and look up the specifications for the oil you will find it is exactly the same as the similar oil without the "Marine". The only "additive" is the price hike for the word marine. <BR> <BR>As for what your engine needs: I am guessing that you are not going to be using your boat in weather that is much below freezing. Therefore you really don't need to worry about the viscosity of the oil or its pourability at minus 20 degrees. <BR> <BR>I am also guessing that the water temperature of the lake you boat in isn't going to get too much above 100 degrees. As long as your water pump is working then your engine is getting a nice flow of cooling water and the engine shouldn't get unusually hot. <BR> <BR>So, in simple terms, you really don't need to use a multi-grade oil at all. <BR> <BR>On the flip side, there is plenty of evidence that the additives used to provide the wider ranges of multi-grade decrease the robustness of the oil. If the oil does overheat, or is contaminated, it can break down and fail. The wider the multi-range, and thus more it is pushed via additives, the more likely this is. <BR> <BR>I would recommend to ignore the "marine" and use either a 15W-40 or 20W-40 oil. <BR>

I'm sure your previous boat also "required" marine oil. But if you ever had it serviced by the SoCal dealer, then it got Castrol motor oil. (20/50w, IIRC)

I just went through this last weekend. To answer your question David, no I didn't find a single quart of "marine" oil in an auto parts store (pep boys, autozone, o'reilys, napa). Ended up with just a standard 15w40 that met all of the specs set forth in the owners manual.

As a couple guys suggested, there is no difference in "marine" oil. <BR> <BR>The easiest way to find 15W40 is to look for oil meant for Diesel trucks. Almost all diesel trucks also specify 15W40. <BR> <BR>Chevron Delo <BR>Shell Rotella <BR>Pennzoil <BR>Mobil Delvac <BR>etc. <BR> <BR>You can find most of these at Wal Mart in gallon containers. Just be sure the one you choose meets or exceeds the specs in the manual (something like SL/SJ, CI-4, CH-4, CG-4). Most likely all will.

I have a Marine Power 5.7 in my boat. <BR>They recommend straight 30 for their engines. <BR>

Use whatever the engine manual says, that's the best way to go. <BR> <BR>My PCM says to use 15W-40, which is the diesel stuff mentioned above, so I use 15W-40, the Delo in particular, it comes in a nice gallon jug, very convenient.

Well if you've done like I have &amp; called several marine service shops &amp; said "Hey, I need to add a quart to my engine. When you guys did the oil change what did you put in it?" Their response: "Just put a good 10W-40 in it".

What about synthetic - like Mobil One? are there any advantages? A marine service tech told me to only switch to synthetic if it is a new engine, right after the 20-hour break in period. A new engine has tighter tolerances and works well w/ the smaller molecular structure of synthetic. I did this with my first boat, and the only advantage is that the oil always seemed clean; didn't break down quickly. <BR> <BR>He also said not to make the switch after the engine has a couple hundred hours, the tolerances are no longer as tight. <BR> <BR>Solid Science..., OR..., Mechanical Mythology?

Most marine engine builders steer you away from synthetic for some reason, and say if you insist and use it, the doesn't change the oil-change interval.

Mobil One at 60-80 hours and every change afterward. Any decent synthetic will do. Older marine oils had defoamers so that water in the oil would not create foam. All oils have them now. Don't get wrapped up with oil - just use a consistent, quality oil and stick with it.

Plus the thermostat likes to get the oil temp above 212F so that any water in the oil evaporates off.

As a rule, you guys are probably right stating that we should be using whatever the engine manual says. <BR> <BR>However, when I was doing the oil change on my '99 Moomba Outback 2 weeks ago, I consulted the Indmar engine manual which stated 20w50. I thought it was a bit odd, so I called Indmar, and they said to ignore the manual, and to use 15w40 as it seems to hold engine temperatures better than the 20w50. <BR> <BR>He also said Indmar's come with Pennzoil, but that I could use any good quality motor oil as long as it was 15w40.

Most boats run at 160-180F.

Multi weight and multi viscosity are the same thing. <BR> <BR>The only thing that makes a motor last longer is the heighest weight you can get where the motor will still turn over. <BR> <BR>The thicker the oil (heigher weight), the more space between metal moving parts. If you could use 90 weight gear oil that would be even better but you wouldn't be able to crank the engine to start it. <BR> <BR>With a boat that never really gets used in cold weather, you could easily run a 40 weight with no problem. <BR> <BR>You only need 10 weight in freezing temps where you wouldnt be in your boat anyway. <BR> <BR>Multi viscosity/weight is really only necessary where temps change.

Elmog, <BR> <BR>Dude you are way off on oil viscosity effecting engine life. More to the point; backwards. Most engine wear occurs between when you start the engine and when the oil is able to be pumped through the oil galleys and onto the bearing surfaces. Heavier weight oil takes longer, when cool, to pump through the engine, causing more wear. Heavier weight oil causes a decrease in gas mileage due to parasitic drag within the engine. It does not protect any better EXCEPT when bearing clearances are too great (due to wear) and the lower pumping pressure causes metal to metal contact on the bearing surfaces. <BR>

With all due respect, this theory; "Most engine wear occurs between when you start the engine and when the oil is able to be pumped through the oil galleys and onto the bearing surfaces." is perpetuated by the "Slick-50" and infomercial additive companies. <BR> <BR>Starting an engine only takes a minute (there is zero load on the engine during starting) and there is enough oil left from previous use to protect the engine (unless it has been a long time since last use (ie winterizing - this is why you spray some fogging oil to lubricate and protect from corrosion)) but running the engine at a minimum of lets say 500RPM (8.3 times per second!) for hours and hours, and then under load at 2000RMPs - this is what will kill your engine (especially if you were running 5 or 10 weight which is what your 40weight breaks down to over time if you skip your oil changes.) <BR> <BR>It is important to understand the numbers in multi-grade oils. If it says 10w-40. That means it is 10 weight oil when cold, and as it warms up, it thickens itself to 40 weight. My Indmar M/C suggests 15w40. This is 15 weight when cold, and heat thickens the oil to 40. It is pretty interesting chemistry that makes something thick when warm. Most liquids, if put on the stove and heat will thin out but they have chemically designed the oil to do a reverse of that reaction. <BR> <BR>They have straight 40 weight at Walmart. If you go and pour out a quart, it will pour just fine and likewise it will pump through your oil galleys perfectly. Basically if you live in Arizona or South Florida, there is no reason to use a multi-grade oil. Because of the ambient air temp, it will always be at its highest weight at anything over 60F. <BR> <BR>If you take that Walmart quart of 40w oil to Nome Alaska and try to pour it out, it wont come out. Then you'd wish you had some 5w or even 1w just so you could crank your engine over (in Nome, even that is not enough and they have to heat their blocks). But basically as soon as it cranks over and gets even marginally warm, you'd want that multi-weight oil to thicken up to it's 40 to protect your engine from wear. <BR> <BR>Respectfully I submit that the best thing for long engine life is a straight 40weight oil (if you will not be in temps below 60F) and frequent oil changes. You can not change your oil too much. - In fact, you'll read and hear all sorts of wives tales regarding oil but the one thing *everyone* agrees on (even the makers of Slick-50 etc) is that freq oil changes are the best thing. But changing the oil is an ass pain so we as lazy comsumers try and hope and pray that if we but a 'fancy 4x4 grade/or a synthetic' oil, we can go longer between changes... <BR> <BR>PS - As for the orig. question regarding 'marine grade' - no difference. Same with oil packaged as for use in 4x4 etc.

I just use Penn 10-40 or any familiar name 10-40 even though Indmar mentions Penn 15-50 "Marine". <BR>I actually pay closer attention to the type and quality of the oil filter, and I usually go w/ Napa filters.

i am first time boat owner of '04 Moomba outback...have similiar concerns w/oil...deciding to change own oil instead of paying arm and leg to dealer located 1 hour away....book says Pennzoil PZ-3 filter...is that a necessity or will another do?? The local Mastercraft dealer (also Inmar certified) suggested a (PF454 - ACDelco filter cause its almost impossible to find and too expensive for the PZ-3 filter)...this looks much smaller than the pennzoil filter already on the boat...suggestions plz..

The PZ-3 is a standard small-block chevy oil filter, and cross-references to almost any brand of oil filter. <BR> <BR>I use the equivalent Purolator "Pure One" on my boat. <BR> <BR>Just grab the oil filter book at any auto parts store and cross reference the PZ-3.

I thought that you want to use the less weight oil when the engine is new due to close clearences of the pistons and as the engine wears go with higher weight to keep good compression. <BR> <BR>Synthetic was made for high hrs\miles since it has a solid in it to coat the wall of the pistons.NOT FOR NEW ENGINES!

to boomer, thanks bro

As stated above, Synthetic after the break in (I would start on the 2nd oil change). That way the rings seat properly.

"Synthetic was made for high hrs\miles since it has a solid in it to coat the wall of the pistons.NOT FOR NEW ENGINES!" <BR> <BR>That's incorrect.

then all the mechanics I talked to over the years are wrong.Tho I'm not a mechanic and can't state neither. <BR> <BR>so Justsomeguy...you want to state why that comment was incorrect and was my 1st statement false as well? <BR> <BR>

Synthetics have a solid in it which can't be good for new engines?

The engineer at Marin Power told me NOT to use Synthetic oil like Mobil One until I had at least 100 hours on the engine. <BR>He said it took this long for everything to be completely seated. <BR>After that he said Synthetic oil is ok, but still do the oil changes at 50 hours. (Why waste the money?) <BR> <BR>David <BR>

I have over 1000 hrs on my 1999 350 MPI Mag. <BR>I change the oil myself twice a season with 15-40w Pennzoil. No apparent loss of oil between changes and the engine still runs like new.

As stated above way up near the top of this page, "When it comes to discussing motor oils there is so much BS, false information, urban legends and old wive's tales that it is impossible to have a reasonable discussion." <BR> <BR>This thread is no exception. <BR> <BR>The "synthetic...NOT FOR NEW ENGINES!" claim falls into this category. <BR> <BR>I've purchased two cars, from different manufacturers that use synthetic as factory fill. <BR> <BR>If "the "NOT FOR NEW ENGINES!" claim was true, why in the world would these manufacturers, and others, use synthetic as a factory fill? <BR> <BR>There's a wealth of info available via Google on the subject. <BR> <BR><a href="http://www.mobiloil.com/USA-English/MotorOil/Synthetics/Myths.aspx" target="_blank">http://www.mobiloil.com/USA-English/MotorOil/Synthetics/Myths.aspx</a> <BR><a href="http://www.quakerstate.com/pages/carcare/whattoknow.asp" target="_blank">http://www.quakerstate.com/pages/carcare/whattoknow.asp</a> <BR>etc. <BR>etc. <BR> <BR> <BR> <BR>

I couldn't make it to my usual Marina and ended up with 25w-40 quick silver but the cap on the engine says 15w-40. Should I take it back and get 15 or will there be a difference? <BR> <BR>Thanks <BR>b

As long as you don't use the boat in cold temps you'll be OK, but 25W-40 is not what the factory recommends, and theoretically they could void warranty, etc... <BR> <BR>Doubtful they will, but it's a risk. <BR> <BR>Once engine is hot the 25W40 will flow the same as 15W40, but it won't flow as well when cold.

Thanks Boomer