4-stroke oil

[Bud G.]

Can anyone give me a reason why I can't use a automotive oil in my Merc.4-stroke like Valvoline Dura-Blend or any other good brand of 10W30 oil?I'm getting tired of paying $3.50 per qt. for Merc.4-stroke oil when I could be using the same oil I use in my pickup.Basically a 4-stroke outboard is no different than many of todays 4 cyl. car and truck engines and should require the same oil.Am I right or wrong?Any opinions or comments would be appreciated.

[Brian/MN]

One reason could be that outboards typically run at idle for longer periods of time than automotive engines. They'd then possibly need oils specially designed to reduce fouling and carbon build-up.

[mwalleye]

Check your owners manual and follow it recommendations. It would be hateful to have problems under warranty and find out its not covered because you used the wrong oil. I think my Yamaha gives specs to follow but not so much that I have to use Yamaha oil.

[MNNICK]

Most four stroke outboards and IO's for that matter are designed to run at extremely high rpm's as compared to auto engines. 5000-6000 rpm on most outboards and around 4500 for many IO's. With that in mind most automotive oils will break down if exposed to that kind of treatment. The marine grade fourstroke oil is designed for high rpm applications. Thats my understanding of it anyway.

[Robertp]

My manual (Merc 9.9) recommends, obviously, using Merc 4-stroke oil. It also lists regular auto oil, with grade and weight ratings, as substitutes. So that's what I use, as did the guy I bought it from. It's a 1996 and no problems I'm aware of.

[Sluggo / NY]

I've been using Mobil 1 synthetic in a Honda 75 four-stroke for three years with no problems. It met all the requirements in the owners manual. I just change it late each fall before I put the boat away for the winter. Good Fishing, Sluggo

[Stan]

As I understand it, the marine vaersions of 4 stoke oil have additives as mentioned before, for high speed (friction modifiers) as well as additives to combat corrosion. The corrosion seems to be especially a problem in automotive block I/O's where they run at lower temps (thermostat temp is lower) than automitive engines. The higher heat tends to cause much water to evaporate in automotive engines. (we are only talking about minute amts of water, not the amounts from a bad headgasket etc).
My suggestionis to use whatever your owners manual suggests, that warranty is much more valuable than the $3/quart you will be saving.

[Ray]

I have a '94 Yamaha Four-Stroke and use 10-40 Valvoline Motor Oil. I change the oil about every 75 hours of use. And this motor runs just as good as Day 1. Pay no attention to all the crap you hear about motor oil. Just keep your oil changed, and you'll have no problem.

[MNNICK]

I don't get it, you pay top dollar for a great four stroke motor and whine about spending probably twenty bucks per year for oil. Ray, as for the "crap" about not worrying about the oil, wanna see some cams that came out of marine fourstrokes that the owners thought they'd save twenty bucks on? It's your motor, treat it how you want, but don't come back on WC and someday say what a piece of junk brand X's four cycles are because it failed.

[Ray]

Listen Mnnick I expressed my opinion. Valvoline motor oil is one of the top motor oils in the country. I use this oil for everything.If you want to waist your money on the other brands that is your business. The oil that the dealers are telling us to use are no better than the oil I am using. For years this oil has been a big mystery. Everybody has there own opinion but nobody can come up with a real honest answer. So guys use your own judgement. If you own a 4 stroke and troll a lot with it change it a lot. If you own a 2 stroke look for the BIA rating that is all you need. If you want to spend more money on other brands your not getting anything better. But I will tell you one thing if you want that 2 stroke to last a little longer burn a little higher octane gas. This will prevent less carbon build up. One other thing Mnnick are you a salesman for these expensive oils?
If you are your not educating me the wrong way. As far as paying top dollar for that motor I bought I am putting in the best oil you can buy. Happy boating Ray

[MNNICK]

Ray, now that you've expressed your opinion, and strongly I might add, The FACT still remains that marine grade fourstroke oil does have certain additives that keep the oil from breaking down and also foaming due to prolonged use at high RPM. Maybe if your running a small kicker motor at idle all day long it's not as imperative. And yes I am a salesman, though not an "expensive oil salesman". Maybe I'm totally wrong, if there are any mechs looking in I'd value your insight into this matter. That is uless your working for the unscrupulous money grubbing MARINE DEALER. (ha ha)

[arny]

if da kinda oil don't matter, do ya think i can use penzoil? if ya don't think so i try and find some of that valverline. what weight shoould i use in mine 1985 50 merc thats one of dem dare
4 piston motors. i been using 25-40

[chrism]

I Second Sluggo's post-
I run the mobil 1 synthetic which eliminates the problems mentioned earlier. It is nice to not have to worry about that stuff. Honda markets a couple of oils for their four strokes - and guess what - the high end one is synthetic.
IMHO, peace of mind is worth the $12 (Cdn$) it costs me to run synthetic.

[Ray]

Arny, Back in 1985 Mercury didn't make a 4-Stroke, you got a 2-Stroke. Yes, you can use Penzoil is a very good oil. One thing, I strongly recommend: use a '89 Octaine Gas. This will prevent less carbon build-up in your motor.

[Ray]

Synthetic oils are fine. One thing, if you use them make sure you buy your motor new. If you use the other oils first, then switch to synthetic, you're looking for trouble.

[scnitzel]

Ray, My friend arnys got a 4 banger not a 4 stoke. good fishin to ya.

[Cliffh]

It seems to me that every oil maker says that their oil has some additive that is special and without it, your engine will fall apart. Yet not one test I've ever seen shows a real difference. Even Slick 50 additive had to back down when the government forced them to "put up or shut up" plus they were fined. If any one oil or type of oil was so superior, why has no oil company ever proven it? I've just used the cheapest name brand oil I could find for over 3 decades. I keep my vehicles for 10 to 15 years and have never had a problem. Why would an outboard be different? Good question. If the manufactures can't tell us, why buy their overpriced oil that they only resell? (they don't make their oil. Who does?)

[Stu Pedaso]

What are those "certain additives"? Chinese herbs? Ground antler from the imature Siberian Silka Deer? I've debated the 2-stroke oil stuff in the past, and I will grant that there is a possibility of certain additives playing a role because of the fact that 2 stroke oil is actually burned as part of the combustion process.
4 Stroke? Same function as a car. Unless you have god-awful rings, you won't be burning oil. Full synthetic would be the way to go, IMO. If you are conceerned about high rpm, viscocity breakdown, etc, then spending $4-$5 quart for a full synthetic would be the smart thing to do. Have you seen the commercials where they fry regular oil in one pan and synthetic in the other? No contest at high extremes. Have you seen the one where they freeze the two oils side by side? Again, no contest at that extreme.
The $10 million dollar question is whether or not the oil ever sees operation in those extremes. Probably not, and that's why non-synthetics continue to perform satisfactorily. Mercury Quicksilver oil is re-packaged Quaker State. They may add a bit of Ginseng or Yohimbe Root so that they can claim "special additives", but no one in their right mind can honestly believe that the chemists down at the billion dollar oil companies (who are constantly striving to improve their product) are not aware of the function and purpose of every single possible chemical additive in existence. And if that additive would improive their oil, they would put it in and get a big fat Christmas bonus and take their kids to Disneyland.
Maximum protection: Full Synthetic
Maximum savings: Bargain natural
Maximum "Not Gonna Dink With It": Manufacturer's Label

[RMB]

Ray could you explain that one. I have a 97' Honda 90 HP and changed my oil to AMSOIL at the 2nd oil change. It's been one year now and no problems that I'm aware of. Now you have me concerned though. Any one know what the dangers are? Am going to change oil soon and need to know for sure.

[REW]

I have to respectfully disagree with a previous post.

With a new motor -- you typically never want to run full synthetic out of the box. The problem is that with the lubricating qualities of a top quality synthetic oil - the motor doesn't get properly broken in.

As you pointed out - after the 2nd oil change -- after the engine is broken in is a good time to change to synthetic oil.

Conversely, if the engine has run for several years on "conventional oil", you want to do something different.
The typical "synthetic" oil has extremely good "cleaning" properties. Because of this -- after a few hours use - with a first change of synthetic oil - you should change it again. The synthetic oil, generally cleans us the engine very well in a few hours use -- and it is a good idea to drain out all of the contaminants that it has cleaned out of the oil. After this change, you can go to the normal recommended oil changes for synthetic oil.

As is the case for my cars - I typically change them at about 12 thousand miles. I change the filter at 6000 miles and add a make up quart of oil. Generally, I will have the oil analyzed every three to eight thousand miles, to insure that nothing is happening to the engine, that might precipate an early oil change.

This reminds me of the case, where I changed to full synthetic oil for his oil injected snowmobile. After driving the machine for about 20 miles, the engine quit - because all of the plugs fouled out. He changed the plugs and came home asking me what I had changed. He was upset, until I explained to him that the oil was simply cleaning out the "gunk" from the previous oils. In the ensuing years, he has never had another fouled plug - and changes them only, when they show signs of excessive wear. Just another example of the cleaning properties of full high quality synthetic oil.

Take care

REW

[Stu Pedaso]

It used to be said that mixing synthetic and natural oil can cause gelling in 2-stroke mixed gas. (I used to race motocross back in the day, and that's what people said) There could be somethign to that in a mixed gas situation.
As far as 4 stroke oil, I don't think it's a concern. Explain Durablend to me. I run full synthetic in winter, but either durablend or normal during the rest of the year. Been doing that for years, and never had a problem. If there was a reaction between synthetic and natural motor oil, you can bet your butt there would be warnings on the labels. Every cleaning agent out there says "test on inconspicuous area first" to prevent liability. If you think changing from natural to synthetic causes engine damage, get a hold of your nearest lawyer. See if you can get the government to stop putting microchips in our drinking water, too.:) For the rest of the people out there, no worries.

[Dave in Mpls]

I disagree.

Synthetic oils should not be used in a new engine. As REW points out, they lubricate "too" well, and an engine does not get porperly broken in. There is absolutely no harm in switching to a synthetic after conventional oil has been used.

Regards

[EyeBoy]

Kudos to REW! On the mark as usual. I run a 4 wynns 245 vista, 502cid (BB GM), 440hp, 514ft#'s of torque. It was broken in on 20/50 Castrol racing oil and then switched to 15/50 Mobil 1 syn.
This eng spends a large portion of its' time running from 3000-5200rpm, when crusing. The oil temp in the sump stabilizes right at 240deg, depending on the water temperature of the lake. At 4000ft altitude she will do 52mph @ 5200rpm (gps). There has been absolutly no problems with the engine, wear wise or otherwise.
One thing that never should be forgotten is that the oil cools the bearings, rods, pistons, cam shaft, crank shaft, valve springs etc as much or more than the water in the jacket. That oil does a heck of a lot of work. Dont scrimp on the oil, or the filter if equipped with one. Draw your own conclusions from the posts, but IMHO syn automotive oil works well.
ON-PLANE!!!TOM