"Making Oil" FAQ?

I get a few customers each year with high oil levels in their 4-stroke outboards and it's really tough to explain why sometimes. So I prepared this to present to customers with the problem and I thought it would make a good FAQ.<br /><br />Q. Why does my 4-stroke outboard oil level keep rising? I never add any. Shouldn't it be going down?<br /><br />A. This is referred to as "Making oil". Here it is in a nutshell. Water vapor enters the crankcase of all motors from the atmosphere, and as a by-product of combustion. In other motors, the oil gets rather hot and any water vapor that may condense will steam-off and exit the crankcase breather. 4-stroke outboard motor oil doesn't get nearly as hot, so the water just keeps on collecting.<br /><br /><br />Q. Is it always water?<br /><br />A. No. Tiny amounts of raw fuel also leak into the crankcase on the compression stroke, potentially diluting the oil and raising the level on a cool-running motor. Or there could be a fuel system leak. Typically the odor of the latter situation is fairly obvious, but not necessarily. Lack of a gassy smell shouldn't preclude checking the possibility of fuel system leaks. Over choking and frequent flooding will also cause fuel to get into the oil.<br /><br /><br />Q. Where does the water come from?<br /><br />A. Three sources. Asmosphere, combustion and fuel. There's always moisture in the air, especially near bodies of water. Some condenses out naturally and collects in the crankcase of a sitting motor. Some comes in right along with the air as it runs. The body of water you're operating on produces a lot of atmospheric water vapor, especially a few feet above the water line ... where the powerhead is. <br /><br />H20 is one of the compounds that forms when gasoline is burned, along with CO, CO2, NOX, etc. Some leaks into the crankcase right along with the other contaminants and mixes into the oil. Alcohol combustion makes mostly CO2 and H2O, so alcohol-blended fuels tend to produce more water vapor than straight gasoline.<br /><br /><br />Q. Wouldn't my oil turn milky if water was in there?<br /><br />A. Eventually it will. But oil has some capacity to retain water and it eventually reaches a threshold where it starts to cloud. <br /><br /><br />Q. Why doesn't the oil get hot enough to steam it off?<br /><br />A. It can. If the motor is running hard enough to plane the boat, water that otherwise cools the oil isn't splashing on the sump that holds the oil. But boats that are run at non-planing speeds may not heat the oil up very much at all. The water the boat is running in cools the oil which is in the sump beneath the powerhead. That water can keep the oil pretty cool just by splashing against the outside of the aluminum sump.<br /><br />Motors that are mostly operated at sub-planing speeds seem to be especially susceptible to making oil. Many times the complaint is that a kicker used for trolling has the problem, but the main motor doesn't. That's because the main motor is used to get to the fishing spot fast to troll slow with the kicker. One is hot, the other is not.<br /><br /><br />Q. Why is it a problem with my motor and not my neighbor's?<br /><br />A. Two things really aggrivate the problem. Cool running temperature of the oil, and the abundance of moisture available that inevitably collects. The environment the boat is kept in, water temperature, the fuel you use, and the way you operate the motor have huge effects on whether or not this is going to be a problem. <br /><br /><br />Q. Wouldn't a hotter thermostat solve the problem?<br /><br />A. Doesn't help much, but it helps. Problem is that you're regulating coolant temperature and not oil temperature. The oil will get a little warmer as a result, but the powerhead will be running hotter and that's probably not good. Then consider that if the sump is getting splashed by water, that pretty much cancels it out.<br /><br /><br />Q. How can I be sure of what is making the oil?<br /><br />A. You can have the oil analyzed. There are many labs that test automotive oil. Outboard readings may not be consistent with what would be expected from an automobile engine, so interpreting the data could be problematic. But it sure will show what is in the oil. A quick search yielded a lot of labs offering this service through the mail for a wide range of prices. Shop around, but it could be money well invested. One site with abundant information is http://www.bobistheoilguy.com/ They also have a Forum if you have any questions.<br /><br /><br />Q. So what can I do about it?<br /><br />A. Right now, the approach is to minimize the amount of contamination allowed to enter. That means keeping the motor as unexposed to atmospheric moisture as possible. Practical in some situations, impossible in others. The manufacturers are also stressing proper and agressive break-in procedures to mate surfaces better and keep leakage into the crankcase (blow-by) to a minimum. Avoid alcohol-blended fuels if you can. Finally, allow the motor to get hot enough to steam-off what water will inevitably collect in there. That'll probably mean running it hard for awhile. (If your lake has a speed limit ... Ouch!)<br /><br />If all of that fails, have the motor checked for gasket leakage. It could be coming from the cooling system. More frequent oil & filter changes may be necessary. But try running the motor hard for several minutes every time you go out. That's the easiest, cheapest, and most enjoyable thing to try.<br /><br /><br />Q. So you mean I HAVE to open it up and go fast once in awhile? <br /><br />A. Dang shame, ain't it? <br /> <br /><br />Thanks to Bill, Bo, DJ, Gary, Jim, LubeDude, Ray, Robby, Rockhopper, TheOilDoc, and of course JB for their encouragement and invaluable assistance in preparing this FAQ.

Re: "Making Oil" FAQ?

I like it, Willy B.<br /><br />Let's see what others might want to suggest.

Re: "Making Oil" FAQ?

I like it for a tech standpoint but in reality,every shop I have talked to about the problem on the 9.9-15 HP tells me that it is gas getting past the rings into oil sump. Yamaha replaced a lot of motors when the first came out w/the 9.9 4 stroke. I talked w/ Honda shop owner this past week again and he said the same thing as before, but added that Honda is suggesting a change of the thermostat every 2 years, he says they tend to start running cold after that. I don't buy that line, but will appease some. I think it is a common problem and for the price of a qt of oil, I change oil about every 25 hours.

Re: "Making Oil" FAQ?

Looks good to me.<br /><br />You may want to mention that it could be beneficial to install an oil temperature gauge to monitor the oil when it is not at optimum temperature, and what that temperature is. An outboard owner with the problem could then avoid running at those speeds/rpm. I realize installing an oil temp sensor on some outboards (like the 9.9's and 15's mentioned) could be difficult.<br /><br />You might also suggest frequent, or more frequent oil changes to outboards that are susceptible to this phenomenon. Maybe list the outboards you think qualify. It seems obvious that outboards that have this problem would live longer with more frequent changes.<br /><br />I understand some of the newer FC-W rated 4-cycle marine oils are more resistant to water and must undergo a special salt-fog test. According to the NMMA, only Mercruiser and Sierra oil seems to be certified for that now, but it might be worth mentioning.<br /><br />Not an uncommon problem with diesels. At lower speeds and idle, engine and combustion temperatures simply are not high enough to completely burn the fuel and rid the engine of moisture. The oil becomes contaminated with fuel and moisture. Thus "wet-stacking".

Re: "Making Oil" FAQ?

I like your FAQ. Does any motor mfg post info on "water making". Might be something to note if they do.<br /><br />Is there any evidence of it happening more or less to engines tilted up during storage? I have a 50 mariner (yamaha head) 4S and never had water making problems. It spends 95% of the time hanging over the water with major moisture exposure. I keep the motor stored down.

Re: "Making Oil" FAQ?

The problem came to light here when the moochers started using the 4 stoke 9.9. You run the engine to hold your boat in the acceptable drift and then when you reach the end of the drift, tilt the motor up and use your big engine to run back to the head of the drift again. Yamaha figured that tilting the engine was causing thier problem. The gas was running out of the carb, down through the rings and into the oil. The replaced 3-4 engines here for my fishing buddies after they siezed for lack of lube. That has kind of gone by the way side since the lack of fish to entice moochers. Mooching seemed to always produce bigger fish, but not as many or as productive as trolling.

Re: "Making Oil" FAQ?

I like it too, Willy.<br /><br />Makes perfect sense and is true, to boot.

Re: "Making Oil" FAQ?

Good job Willy. Took you some time. I suppose that it must be water, if the oil doent smell gassy. Sure hard for me to believe that the engine could make that much water, and it would find its way into the sump area and actually be in quantities enough to actually raise the oil level though. You know your stuff though, so I guess anything is posible.<br /><br />I always thought "Wet Stacking" was when diesel built up in the exhaust system, not moisture. Not trying to start a rift, just trying to clarify.<br /><br />I checked the Yamaha site and they dont want to recognise the problem.

Re: "Making Oil" FAQ?

I read the FCW-4 specs ( http://www.nmma.org/certification/programs/oils/fc-w.asp?bhcp=1 ) and , as I read it, does not cover any issue with water ingress into the oil. In the scope the only reference is to a fuel dilution of 7% during the tests. The salt fog tests are , I believe, designed to asses an oils ability to withstand corrosion on exposed surfaces with its ability to "cling" to a surface. I can see how water ends up in oil and have no problem with the pricipal but my suggestion is that the word moisture should be replaced with contamination. Contamination being defined as either liquid gasolene or water or both. The NMMA quote " corrosion and fuel dilution has been identified as a field concern". Interestingly there is no reference to add fuel to oil , only that fuel dilution should "reach a minimum of 7% after the 50th test hour" to a maximum of 15%. Do we assume that Yamaha are happy stating that a 10% contamination will occur regardless ??

Re: "Making Oil" FAQ?

We will se if rodbolt has anything to add. He has written some answers to questions in the Yamaha forum about Yamaha F115 making oil problem.<br /><br />But to me the contents of the FAQ above make sense.

Re: "Making Oil" FAQ?

Thanks for all of your input, gentlemen. It is most appreciated. I edited in quite a few revisions based on your suggestons. Keep 'em coming ... <br /><br />There is something simple, cheap, and easy that I'd like to see and I hope some OB engineers read this. I'd like to see a baffled sediment chamber cast into the sumps at the drain plug. If settled water isn't allowed to mix in with the oil, then it could reduce the problem. It would also give water a place to go and not get sucked up by the oil pump and trash the powerhead. Put an electrical sensor in there (same one used on Merc fuel filters) to detect raw water and send a warning signal to the alarm. And an easy way to remove it. Simple! Cheap! Easy! Do It! <br /><br />I was also wondering about a pan to catch the oil as it runs back into the sump. Hot oil collects in a pan and overflows down to the cool oil. An Evaporator if you will.

Re: "Making Oil" FAQ?

Member rockhopper, you are correct that the FC-W rating will not include testing for direct ingress of water into the crankcase. However, I think it is worth mentioning that using FC-W rated oils in outboards with this phenomenon would be beneficial. FC-W oils appear to be more resistant to water corrosion, a primary effect of the water in crankcase phenomenon.<br /><br />Unlike other oils, FC-W oils take into consideration high levels of exposure to humidity and salt water. The salt fog test includes placing metal coupons in a humidity chamber where a sodium chloride solution accumulates on the coupons at a rate of 1-2 ml per hour for 24 hours at 95F. FC-W also requires the oil to perform where there is an increased propensity for moisture and corrosion, and the unique characteristics of the marine environment.<br /><br />Concerning wet stacking on diesels. I have professionally evaluated oils from large diesel generators and marine engines that frequently idled long periods. Water content was a primary component, both in the crankcase and in the exhaust system. Diesels use a lot of air. Air contains lots of moisture. Unless the engine is periodically loaded to operating temperature, the moisture can not escape the engine via the crankcase ventilation system or the exhaust system. The results of wet stacking go far beyond just unburned fuel. This is not unlike the moisture we see come out of a gasoline engine's tailpipe, which can eventually rust out an exhaust system.

Re: "Making Oil" FAQ?

I rather accidentally observed something I thought strange. I saved a sample of some thusly contaminated oil in a plastic Coke bottle, about half full. The cap was tight. The longer it sat, the more the bottle puckered. I burped it a couple of times and it did it again and again. It sat on my bench all the time and the temp was fairly constant. I was also waiting for water to settle out, but it never did in the few months I had it on my bench. But it was weird that the volume seemed to decrease and started to pucker the bottle. Unless the oil was expanding the plastic bottle?

Re: "Making Oil" FAQ?

I would think that the expansion was caused by gas in the oil. The liquid gas is turning to fumes and causes pressure to increase in the bottle. thus you pressure swell. You see the same thing with an air tight gas can when the cap is on tight and fumes are not allowed to escape.<br />Any of your liquids will to that, look at liquid oxygen/nitrogen, they have something like 250 to 1 expansion rate.

Re: "Making Oil" FAQ?

I would still like to have seen some sort of test that showed an oils ability to hold water in suspension whilst under load without a great loss in stability, although I have no idea what that test might be.<br />Willy try a sample test , some used oil from a "good" engine , some from a "bad" one. Put them both somewhere warm, cap off on a windowsill for example and see if after a couple of days one has dropped more than the other. Both will drop but the "bad" oil should go down more. If the NMMA numbers are anything to go by , the "bad" oil may have more than 15% of the content gasolene.<br />I wonder if a used oil analysis (UOA) would be beneficial here. There are several that will do a breakdown and put some actual numbers to water and gasolene , also tell you if the bearings are falling apart . Have a look at http://www.blackstone-labs.com/eng_balloon_report_.html , I'm sure other companies produce something similar. The $20 upfront might be money well spent.

Re: "Making Oil" FAQ?

Thanks, rockhopper. The oil should defiantely be analyzed if it is cost effective. Hundreds of dollars, no. Twenty bucks? You bet! I'm going to do some searches. But that is definately something I'll add. <br /><br />Gentlemen, any information regarding getting oil samples tested and the cost would be most appreciated. Links and/or your experiences.

Re: "Making Oil" FAQ?

Great post..(remember guys, it is written for the guy on the other side of the counter) and ..<br />Willy...More frequent oil & filter changes may be necessary. <br />Oil Doc..You might also suggest frequent, or more frequent oil changes <br />Some one need glasses? (feel the friendly nudge?)

Re: "Making Oil" FAQ?

Originally posted by gss036:<br /> expansion was caused by gas in the oil. .

Click to expand...

Actually just heat and/or atmosperic pressure is the main cause. Put a tiny splash of gas in a plastic gas container and set it in the sun after a storm for some fun kiddy kemistry!

Re: "Making Oil" FAQ?

Did the Coke bottle pucker in or pucker out? If it was in it was probably due to temp. Hot oil makes hot air- then you close lid. Oil cools, air cools, pressure decreases, Coke bottle volume decreases, bottle puckers in. Same thing would happen with a half bottle of hot water left out, try it. In reverse if you partly crushed the bottle and put half a bottle of cold water in, closed the lid and put it in the sun to warm it would pucker out.<br /><br />Maybe an answer to some of the oil making is to put a crankcase heater in them like they do up in cars up north. I wonder if this making oil problem is worse up north or if it occurs down here in Florida. Cars have oil coolers, maybe the outboards need oil heaters (actually temp regulators would be more accurate) like WillyBWrights evaporator to keep the oil at operating temps. They could be thermosatically regulated so the oil didn't get overheated, basically the same as the water cooling system. You don't want your blocks water to be too cold and maybe in some 4-strokes the oil has to be treated the same way.

Re: "Making Oil" FAQ?

I don't know if this is a factor with outboards but when living in Alaska working with autos if the engine got flooded when trying to start cold or if there was a manual choke and it was not used properly the engines could make a lot of oil!