What’s everyone’s opinion on which oil to use for older 4 strokes?

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StefanYHU

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I’ve a 1999 Honda 4 stroke, and my father is very much along the lines of throw in any 10w30 that you would be happy to use on your motorbike and that marine oil is a
Con etc

I can get Castrol 10w30 power 4t cheaper than any marine oil and can buy it significantly cheaper in larger quantities.

I’d be specifically interested in hearing from those who have run these engines for significant periods of time and those that do the work themselves......as I know those who only use dealer services, we going to side on marine oil as it’s the only thing they know
 
Any old 10-30 is the answer. Marine oil? Wossat, except as you say far more costly? The only thing that matters (and not a great deal at that) is the viscosity. In an agricultural engine like your Honda I'd use the cheapest oil of the correct grade I can find. The engine won't know the difference as long as you change it at the stipulated intervals. If it was to run all day every day I'd be undecided whether to give it something with a brand name but if I did it would be Morris's
 
I used Shell Helix fully sync 10/30 in my Honda 30, it was thrashed to within an inch of its life, daily, no problems at all, but i changed the oil regularly.
 
My car's done 100k on 2 oil changes of the cheapest oil I could buy. I do change the boat's diesel engine oil every year though.

What i'm saying is you'll probably do more damage to an engine by low oil than the wrong or old oil.
 
What 4 stroke is it?
The 'correct' answer will vary according to the size of the engine.
Small engines without a full-flow oil filter should ideally be run with a non-detergent oil.
If you change to a detergent oil, then the oil may get very dirty, very quickly.
There is a lot of confusion regarding 'straight' oil being either monograde or detergent free, depending on context.

In practice, I'd probably use a semi-synth detergent multigrade and change it often, because I doubt it will get run many hours per year.
A big outboard with a proper oil filter is different. Might run a lot more hours in a year.
 
Any 10/30 oil is suitable. Depending on model Honda tend to use high amounts of silicone alloys in engine construction. I actually are not a fan of Honda own brand 10/30. It tends to leave a residue and can solidify if service intervals have been missed, as well as being over priced!!
 
Your engine, your choice.

Would you walk through the High Street and ask a stranger about your health issues? Or is it a case of searching weather forecasts on the interweb until you find the one that suits you best? ?

What does the engine maker recommend? Any reason to deviate away from his recommendation?

If the recommendation gives a viscosity and a spec, you can buy any oil that meets the same specs. If the recommendation is very type-specific and includes an additive, I’d consider that the additive is required for a good reason.

Not necessarily a commonly held view but perhaps safer than relying upon good fortune.
 
steve66 said:
Any 10/30 oil is suitable. Depending on model Honda tend to use high amounts of silicone alloys in engine construction. I actually are not a fan of Honda own brand 10/30. It tends to leave a residue and can solidify if service intervals have been missed, as well as being over priced!!
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Not sure of the implication of "silicone alloys" ( I think that you probably mean aluminium- silicon alloys which are commonly used for casting components for i.c. engines) but I can't see any impact on the choice of oil. I've owned and currently own a number of Honda engined devices but never use their own- brand oil. I use any one of a range of respectable makes of the recommended viscosity.
 
Any engine that relies on non-hydraulic tappets needs an oil that clings to impact surface. If it drains down between uses it will cause excessive wear on starting. You need decent levels of zinc and phosphorous in the oil. (Zinc dialkyldithiophosphates- ZDDP- It also provides corrosion and oxidation protection. However, because the zinc and phosphorus found in ZDDP can negatively affect catalytic converters, it has been phased out of motor oil formulations in recent years)

So for an older or low tech engine stay with mineral oils. Some Classic Car oils have raised levels of ZDDP for better protetction of impact surfaces. They are often cheaper than modern motor oils Heritage 20W50
Comma do one and several other companies do. Any pushrod engine will benefit from their use.
 
The viscosity rating and the alphabet soup that comes after it is the only pertinent information needed, for petrol engines you're looking for API SJ or better(higher in the alphabet, so SK is better than SJ etc). The FC-W marine oil thing seems to be largely a product of the marketing dept, they claim it has many wondrous qualities the only one even vaguely plausible is having corrosion inhibitors added.
 
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