automotive oil in 4 stroke outboard

[whaler nut]

I see that there is specific oil at the marine store for 4 stroke outboards. Whats the harm if you use a premium automotive oil of proper viscosity and keep oil changed regularly???
(1999 Honda 40HP)

 

[TOHATSU GURU]

Re: automotive oil in 4 stroke outboard

None.

 

[Lundman]

Re: automotive oil in 4 stroke outboard

I am not sure I would agree with that. They say that automotive oils will not
stand up to the rigors of marine use. Friend,I would use either Mercury or
Tohatsu FC-W 10w-30 or what ever the manual says you should use. Me,to
be safe,I would spend the extra money and use the motor manfacturer's oil
that is/designed for that particular motor.

 

[TOHATSU GURU]

Re: automotive oil in 4 stroke outboard

There is zero negative effect from using a non FC-W oil in a four-stroke outboard... FC-W oil has only been out a few years and up until the rating was issued there wasn't a problem with it. Having said that, FC-W oil helps to reduce fuel dilution and foaming....But that wasn't the question. The question was:

"Whats the harm if you use a premium automotive oil of proper viscosity and keep oil changed regularly???"

And the answer is still none.

 

[JB]

Re: automotive oil in 4 stroke outboard

What TG said.

I used Mobil 1 in my Suzi DF70 and had no problem, but I understand that 4 stroke outboard manufacturers recommend not using synthetic as they think it increases the oil dilution problem (that I did not have).

 

[Lundman]

Re: automotive oil in 4 stroke outboard

There is zero negative effect from using a non FC-W oil in a four-stroke outboard... FC-W oil has only been out a few years and up until the rating was issued there wasn't a problem with it. Having said that, FC-W oil helps to reduce fuel dilution and foaming....But that wasn't the question. The question was:

"Whats the harm if you use a premium automotive oil of proper viscosity and keep oil changed regularly???"

And the answer is still none.

So then,...what you are saying that if I,for example,were to choose either Merc,Yammie,Honda,Tohatsu,or whatever four stroke outboard I would by
that if I were to go to Wal-Mart and by Valvoline 10W-30 premium conventional automotive oil,it would be okay to use in a four stroke outboard
provided it recommends 10W-30,and I keep the oil changed on a regular basis,
there would be no harm done to the motor? Maybe it's just me,...but I would
feel alot safer using the manufacturer's oil,...especially while the motor is under warranty.

 

[TOHATSU GURU]

Re: automotive oil in 4 stroke outboard

The short answer is yes. The long answer is that you would be better off using an FC-W rated oil. The key here is the word "harm"....I don't fault you for assuming that factory oil is better for an engine. Chances are it is for most people over a lifetime of use.

 

[mickjetblue]

Re: automotive oil in 4 stroke outboard

My 2 cents is I have used auto oil for 8 years, and I think my 4 stroke is
running better now than when I bought it. I change it each spring.

I doubt if you'll see a post from anyone stating that their motor was
harmed from using auto oil changed regularly.

Interesting thoughts are thought provoking, all the same.

 

[jay_merrill]

Re: automotive oil in 4 stroke outboard

My 2 cents is I have used auto oil for 8 years, and I think my 4 stroke is
running better now than when I bought it. I change it each spring.

If your boating season is short enough to warrant only one oil change per year, I would change it in the fall rather than the spring. Leaving dirty oil in your motor all winter doesn't seem like a good idea to me.

 

[gss036]

Re: automotive oil in 4 stroke outboard

I read somewhere that it is best to use the 4 stroke because most the 4 stroke motors run too cool and collect moisture if not run at higher speeds and also helps with ones that make oil from oil dilutition. I have always just used regular oil in my 15 hp Honda and changed about every 50 or so hours as 95% of my running is trolling at about 2 mph.
My boat is in the shop this week getting a new 225 HP Honda installed. I will have to try and remember to ask about the pros and cons to see what they have to say. I know Honda reccomends using 4 stroke oil.