I run Amsoil synthetic in my 4 stroke kicker. I changed the oil last fall before I stored it for the winter. I only troll with it when the wind is too strong for my bow mount so it's only been run 4 times all season. I was figuring out what I needed from the store to winterize my boat this weekend and I checked the oil in the kicker. Visually, it's as clean as the day I poured it in. I know that cars can go much longer between oil changes when they're run with synthetic. Can a gently-used 4 stroke kicker go two seasons with it?
Synthetic Oil - How often do you need to change?
Read into it what you want but we have $250k tractors and use hours not time as indicator when to change. 300 hour oil for me is several years of use and only use the tractor for specific farm task so sits long periods between uses. Break in period is lower hours so after broken in with good oil and filters I have no problem running the oil longer. Now our neighbor uses my waste oil for heat and we use some for use on combine heads, but when changing our semi and tractor oil with deep sumps takes some major amounts of oils. I know the oil man would love yearly oil changes from farmers... But it isn't happening for a reason.
Under warranty they note to change breakin oil early, afterwards based on hours and how it is used. Car I change every 10k miles, now the owners manual notes every 5k oil is prob good for 15k but 1/year oil changes and I keep cars into 250k mile range w/o any problems. Can change oil filter and keep oil as well if pushing envelope. Neighbor runs 15k on Mobil one and has several vehicles over 500k miles. He purchased a used southern truck for the body panels because WI salt was getting to his ride but engine is no problem.
End of season I would run up the RPM and burn out any moisture in the oil to be safer and store dry. Look for foaming on the oil fill cap for signs of water issues and if any questions change it. Most lawnmowers never see a oil change.... Today's oils are great but not a lifetime oil yet. Even my lifetime minivan trans oil gets a dump and fill seasonally as insurance as the filter is more of a screen and I tow over capacity of the van on a reg basis. Trans deal with more shear and good to keep the modifiers not broken down. 4 times / year I would change every 2-3 years. Use a white paint marker and not last oil change so you have a reminder when it was done last as a good practice.
Synthetic oils can cause problems with new kicker engines. It's hard to get the motor to break in with synthetic oils. Some mfgs don't recommend them until the motor is broke in. With kickers this can be an issue. They hardly get run at high speed.
Moisture and fuel contamination are more of an issue for kickers than oil breakdown.
I usually recommend kickers get run at full throttle once in a while to get the motor and oil up to full operating temperature. This will help deal with moisture and fuel in your oil. It also should be run at full throttle to make sure the rings are broke in.
A visual check after running will give an indication of water/ condensation in your oil.
If you are getting fuel contamination you'll usually see your oil level increase. Sometimes you can smell fuel in your oil
Synthetic oil or fossil oil is cheap when compared to the cost of a replacement motor.
I changed the Mobil One I ran in a Honda 9.9 Power Thrust twice a season. The total cost for oil and a filter was less than $20.
Chances are if you only put a few hours on your OB trolling motor your not burning off any fuel that finds it's way into the crankcase. That and other acidic compounds that are in the oil from fuel combustion make a yearly oil and filter change just good preventative maintenance.
I'd highly recommend changing the engine oil, oil filter (if your motor has one) and the lower unit oil every fall before storing. Runs some Sta-Bil in the fuel and run the gas out. Pull the prop and grease the splined shaft too.
I doubt if there is much if any breakdown with that few hours. One of the reason one uses synthetic oil is its longevity and the ability not to break down. And with that few hrs of use I'd say you are throwing your money away by changing that often.
If you want to change it that often then put that used oil into your car/truck and put 5000 miles on it because it's still good.
Changing the oil and filter every spring is cheap insurance.
Only used 4 times a yr? If that's the case I'd change it every 5 yrs. Do you think that the oil breaks down just sitting there? Unless you get water in the crank case that oil should last you a good long time using as gingerly as you say.