winterize 90 hp outboard

twologs5

Cadet
Joined
Oct 13, 2016
Messages
17
new at this wondering about winterizing 90 hp mercury 4stroke efi I suspect change oil and filter drain and replace lower unit gear oil grease all nipples lube steering controls my question is about fogging engine is it better to run and induce fogging oil into engine or remove plugs and do manually I have read that fogging efi engine is not proper way comments also I added fuel stabilizer last trip out unit ran for couple of hours at least also ran premium fuel all season I am a licenced car and dieseltruck mechanic
 

ezmobee

Supreme Mariner
Joined
Mar 26, 2007
Messages
23,767
I have never fogged any of mine and haven't had any issues. The other things you listed are good things to do.
 

SkiDad

Lieutenant Commander
Joined
Jul 18, 2010
Messages
1,518
i used to spray fogging oil into a running engine - now i just pull my spark plugs and spray some in each cylinder and rotate the flywheel a few times.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
i used to spray fogging oil into a running engine - now i just pull my spark plugs and spray some in each cylinder and rotate the flywheel a few times.


That method doesn't help much, all you're doing is putting oil on the bottom side of the cylinder, maybe 1/4 of it. And if its a two stroke it needs the extra oil in the crankcase, this method totally bypasses it.
 

Watermann

Starmada Splash of the Year 2014
Joined
Jan 12, 2013
Messages
13,822
Is your boat being stored outside over the winter? One thing is to make sure the motor is tilted all the way in so any water will drain out and if stored outside keep it that way so water won't collect and freeze in the exhaust.

Fogging oil is only effective when like said above sprayed into the motor while running. You're motor will be fine, I would only use fogging oil on it if it were to be stored long term.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,592
Mercury in their service manual suggests removing spark plus and injecting some oil in each spark plug and rotating engine.

They do not suggest using fogging oil on a four stroke fuel injected engine.

I never bother. I just change the engine oil and filter, lower unit oil and change the fuel filters and I am done.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
ig step
Mercury in their service manual suggests removing spark plus and injecting some oil in each spark plug and rotating engine.

They do not suggest using fogging oil on a four stroke fuel injected engine.

I never bother. I just change the engine oil and filter, lower unit oil and change the fuel filters and I am done.



On a 2 stroke if you have fogged the motor first and then add oil through sparkplug hole you're good, if you dont fog it first you missed a big step, after saying that I rarely, if ever fog.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,592
ig step



On a 2 stroke if you have fogged the motor first and then add oil through sparkplug hole you're good, if you dont fog it first you missed a big step, after saying that I rarely, if ever fog.
OP has a 4 stroke.

I am quoting the Mercury factory service manual for 4 stroke EFI and they don't say to fog.
 
Top