4 Stroke engine oil options

I have a Honda BF15A 15hp 4 Stroke and was about to do an engine oil change and realised I have SAE 10W-40 but the owners manual recommends SAE 10W-30.

Its an old outboard nearly 10 years now, and noticed that 10W-30 oil is hard to come buy, is this because to new stuff is better for the engine?

Any advice before I go ahead and drain and refill it would be appreciated.

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Date Joined: 09/08/09

You can have a nice read here

Wed, 2011-12-21 14:40

You can have a nice read here if you want. http://www.upmpg.com/tech_articles/motoroil_viscosity/  Basically the higher the second number is the thicker the oil is at engine operating temperature, which is better for the engine. There is a trade of for the better protection at operating temperature as the thickening additives deteriorate making the oil thinner over time (lowering the second number) which in your case is what you want. :) So after time your 10w-40 will become 10w-30.

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76

Fri, 2011-12-23 08:30

i have just done my merc's with castrol boating plus and it exceeds all merc's standard's.hope this helps .

mlayton76's picture

Posts: 29

Date Joined: 19/12/11

All is going well

Tue, 2011-12-27 22:33

 Thanks for the feedback guys, I've done the change now and all is going well, it most certainly needed a good clean out!

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Date Joined: 20/08/10

See you've done the oil

Thu, 2011-12-29 21:09

See you've done the oil change already but thought I'd add my 5c for next time. I bought a 4.2m tinny with a Honda BF25A outboard a couple of months back and wanted to do an oil change.

I went through the exact same thing, looking at the 10W-40 and wondering if it would do. In the end I went into a local boat shop that is a Honda Dealer (in Wangara) to get the oil filter and they had Honda branded 10W-30 oil. I assumed it would be a lot more expensive but was only fractionally more than the cheapest 10W-40 oils I'd seen, especially considering the tiny amount that you actually need for these smaller engines. 

Had a good chat about my engine with  a very helpful guy there and walked out with Honda branded fuel filter, oil filter, motor oil and gear oil (enough for 2 changes) for about $80 from memory. 

I'm no brand whore, but there is a certain amount of peace of mind to be had from using manufacturer branded parts and oils.

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Date Joined: 19/12/11

Branded parts are good piece of mind

Sun, 2012-01-01 16:10

Thanks tigerfish, 

I also use honda branded parts on most occasions, impeller, fuel and oil filter etc... I agree that sometimes the small amount extra for the peace of mind and good service work well. I have been using a hinda dealer SOR for my spares.

I have learnet quickly with boats that its much like a wedding, the prices are based on how much you actually know about the stuff as to what you are charged. I had a water cooling problem on the same outbpard, first time cost me $200 for a dealer fix, second time cost me $3 to do it myself and I learnt heaps about my boat at the same time. Now I only get the mechanics to do the difficult stuff and do the rest myself.

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  Agree completely regarding

Mon, 2012-01-02 20:46

  Agree completely regarding variable prices depending on how confident or knowledgeable you sound. When I was ringing around for the oil filter, I asked (mainly out of interest and for the satisfaction of knowing how much I was saving by doing it myself) how much it would be for them to do the  oil & fuel filters, engine oil & gear oil. It was incredible the variation from dealer to dealer, and in one case even from two different guys at the same dealer!

On a separate issue, I wonder if you can help me with a bit of advice since you have a similar set-up to me (small Honda 4st and tinny). I bought my rig used a couple of months back and it goes well overall, but I have found that when I am accelerating to get on the plane, I have to do it quite gradually by feathering the throttle otherwise it seems to 'bog down' (revs drop off). The engine seems to run fine all other times, and to me it seems more like the engine is struggling with the load rather than a fault. If you were to open up your throttle quickly from a stand still with a heavy load on board, does your outboard rev up freely or does it 'bog down' like mine?

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Date Joined: 19/12/11

Getting on the plane

Sat, 2012-01-07 20:40

 Hey Tigerfish, 

I took my tinny out the other day and tried what you said about opening it up flat out from a stand still, it does bog down a little, say the first 10 metres or so but then does get up on the plane. Mind you if I ease the revs on, low, meduim then high it gets up much easier. I am usually only out by myself or with one other and have probably an average amount of gear with me, similar to you by the sounds of it. 

I did notice a difference the other day as I stripped the fuel system to clean it from top to toe and decided to give premium unleaded a try for the next tank, it made a difference immediately, ran quietier, smoother better acceleration as well. So for me the extra few cents per outing is worth it. That might be something you could give a try. Also have you looked at the pitch of the outboard, mine is a manual adjustment so have set it up for an average day on the water, its not perfect but it will do for most situations. 

If you want to know any more about the maintenance on your outbaord and get stuck let me know as I am slowely working my way though a full overhaul on it bit at a time and have worked some of the tricky bits the hard way. 

Mark 

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 always use premium unleaded

Tue, 2012-02-07 04:17

 always use premium unleaded as over time the octane level will drop. ie regular 91 over 2 months can drop to as low as 75 octane. unless you are out weekly refill each trip out with 98 octane. told by mechanic/ boat owner mate