Synthetic oil in Honda 8 HP 4 stroke

[Chuck1313]

Guys,
I am thinking of switching to synthetic oil in my Honda 8 hp 4 stroke.
Should this be fine or better than regular 10W30 oil in the engine?

Thanks for the help,
Chuck

 

[TOHATSU GURU]

Re: Synthetic oil in Honda 8 HP 4 stroke

Synthetic would be a huge mistake...Huge.

 

[Chuck1313]

Re: Synthetic oil in Honda 8 HP 4 stroke

Why would it be a "huge" mistake?
Please explain your reasoning.
Chuck

 

[TOHATSU GURU]

Re: Synthetic oil in Honda 8 HP 4 stroke

Synthetic oil contributes to the engine running cooler than it is supposed to. That leads to fuel dilution into the crankcase. That leads to premature wear. That leads to boom. Synthetic oil is just a waste in a raw water cooled engine. No outboard manufacturer will recommend it.

 

[walexa]

Re: Synthetic oil in Honda 8 HP 4 stroke

I disagree........the oil does not control the engine temperature, the thermostat does. What I have read on this forum is Honda doesn't recommend the synthetic oil because it does not want owners to try and run extended service intervals that are typically associated with synthetics, i.e., keep the same maintenance schedule they recommend.

What I do agree with that with raw water cooling and keeping with normal service intervals I don't know that anyone would see any real benefits from synthetic, unless you live and boat in extremely cold weather, where you should experience easier starting.

But synthetic oils are better........run what you want with the proper API certification recommended by the mfg and maintain recommended service intervals and you will be fine either way.

Waylan

 

[gss036]

Re: Synthetic oil in Honda 8 HP 4 stroke

You are only talking about 1 qt of oil, use regular oil and change it every 25 hrs. I think you would be much better off. The biggest complaint w/4 stroke motors are the fact that they do "MAKE OIL" and using synthetic would add to that. I have fought that for years with my Honda and clean out the stat at least once a year, sometimes more often. The only way to get around that is to end every time you use the motor trolling is to run it at high spped for a few minutes to raise the temperature and vaporize the gas build up. Just my nickles worth.

 

[TOHATSU GURU]

Re: Synthetic oil in Honda 8 HP 4 stroke

"I disagree........the oil does not control the engine temperature, the thermostat does."

Yes and no. The thermostat attempts to regulate the cooling system by restricting or opening within its design parameters thereby keeping the engine within its operating temperature. Unfortunately, in outboards, they have less than perfect success. Synthetic oil does its job too well and tends to reduce the friction and therefore heat, below engine design specs. Its a small difference and depending on a lot a variables may or may not be an issue. But, considering the short oil change intervals, expense and the fuel dilution that it exacerbates...There is no reason to use synthetic in a 4-stroke. And since one outboard manufacturer flat out tells you not to use it for the reasons I have stated.....It's just not a wise decision.

 

[tmartin]

Re: Synthetic oil in Honda 8 HP 4 stroke

Ok, you guys are killing me!

The past two kicker motors that I have used, have been a BF8D and a BF15D. I am in pretty cold water temps, maybe you guys are or not. My ocean temps are from 48-61 degrees. Mostly 50-53 degrees. I have done extensive research on this "making oil" issue. I have discovered that there is a way to counter-act the cold water temps and (Mobil 1 synthetic) WHATEVER oil you use. I had factory oil that "made oil".

Honda uses two thermostats. 60degree CELCIUS, and 72degree CELCIUS. Interesting to note, they're all (thermostats) the same size too. Anyway, goto the parts counter and ask for a 72degree stat for a BF90 (say 2006). Go home remove the Top left side, 2, 10mm nuts., pop out the 60 put in the 72 and all will be right with the world!--AND you can SAFELY use that "ever-cooling" synthetic oil for the BEST protection that money can buy.

Tom

 

[gss036]

Re: Synthetic oil in Honda 8 HP 4 stroke

Tom, I did that a long time ago and they still make oil, there is just no getting around it when trolling at 1.8-2.0 mph for 5-6 hours at a time. I try to take the time and run almost WOT at the end of the day and that does help. I still suggest changing the oil more often if the key. If you watch the rebate specials w/different stores you can still get oil for around a buck a quart.

 

[hondon]

Re: Synthetic oil in Honda 8 HP 4 stroke

Now that we've all agreed that these engines make oil and that no outboard manufacture is falling all over themselvles reccomending them ,let's consider why.Typical auto oils are made to maintain emmision standards including the synthetics.That means that they lack some of the dispersants nesseesary for a marine evironment where the the engine is exposed to saltwater mist ,exhaust intrusion,fuel comtamination,and extended low speed use in often cold water.That not only means you will get some fuel in the oil but moisture as well.If those dispersants are not there ,what then?Look for oil with an FCW designation.