Engine Oil Weight Rating on Outboard Engines

My manual calls for 10w-30 engine oil that has detergents.



I bought Castrol 5w-30 in a synthetic blend because they didnt have it in the 10w-30. I know the temp range 30 is good but worried about the Weight 10w vs. 5w I bought.



1) Will the 5w work?

2) does anyone know if Castrol Synthetic blend has detergents? not sure what that means.

Re: Engine Oil Weight Rating on Outboard Engines

It will work and it does have detergents. 10w-30 is pretty easy to find in my area......

Re: Engine Oil Weight Rating on Outboard Engines

What type of motor? I/Os and four cycle Outboards usually require FC-W oil, which is much heavier duty than auto multi vis oil. Alternatively SAE-30 motor oil is usually acceptable to use in I/Os.

Re: Engine Oil Weight Rating on Outboard Engines

Its a 2003 honda 4stroke fuel injection. Manual actually calls for a SAE 10w-30, from what I read w stands for winter not weight. I believe i should be fine, but correct me if im wrong. the API CERT in the manual says SN, and the synthetic blend from castrol shows the SN as well.

Re: Engine Oil Weight Rating on Outboard Engines

jbjennings said:

It will work and it does have detergents. 10w-30 is pretty easy to find in my area......

Click to expand...

haha,I didnt feel like driving around, but thanks for the info!

Re: Engine Oil Weight Rating on Outboard Engines

W does not stand for winter.

Be careful with straight 30w oils, many of them are non-detergent.

Also, API SN does not stand for synthetic or semi-synthetic, it's just the next letter in their oil classification system. Previous was SM. You would be fine with the 5-30, but in the florida heat I would have gone for the 10-30 the manufacturer calls for.

Re: Engine Oil Weight Rating on Outboard Engines

Sorry 444, but W in 10W-30 does stand for winter. That motor oil thins to an SAE 10 when it is cold, and thickens to SAE-30 when the motor warms it up. 444 is right that you need a detergent motor oil, and some SAE-30 oil are non-detergent.

However, it is likely your motor calls for FC-W (four cycle - Water cooled), which is heavier duty than standard auto multivis oil. Obviously you may use what you want, and maybe the FC-W designation is a scam, but I for one would follow the manufacturers recommendation.....

Re: Engine Oil Weight Rating on Outboard Engines

If the manual tells you what to use, why on earth would you ask if something different would work? The manual knows better than anyone on the internet.

If you can't drive around to find the right one, google e-bay, right one, CC# and it'll be at your house in 5 days or less. Or just use wallyworld 100w50xTCW3 and you'll just be fine.

Re: Engine Oil Weight Rating on Outboard Engines

One of the reasons for the differences in water craft oils is that, unlike automotive applications of similar engines, the watercraft is expected to run at full throttle for extended periods of time. Autos don't do that so there surely is some distinction in the oil stocks or detergents/additives for the applications.

Concerning your question about will a 5w work where a 10w is specified, my truck manual specifies 5w30. I use Mobil 1. My last oil change I bought 0w30 and on the container it said something to the effect that it will satisfy OEM warranty specs for 5w or 10w. Course when it's cold you want thin oil and what that says is that there is really no lower limit to that oil's ability to remain thin. Remember, viscosity in oils is all over the place and the colder it is the higher the viscosity (orders of magnitude), the thicker it is, and the harder it is to lubricate critical parts upon engine startup.

Mark

Re: Engine Oil Weight Rating on Outboard Engines

For what it's worth, here's the recommendations for the OP's 2003 200hp Honda Outboard:

Re: Engine Oil Weight Rating on Outboard Engines

Interesting that Honda does not specify a FC-W oil. Every other manufacturer I saw did specify FC-W oil....Sounds like you may run any 10W-30 automotive oil in that motor