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Engine Oil Question

I'm new to boating and wish to change the engine oil and filter on my Nanni-Kubota type 4.15 (37.5hp - 1498cc) engine. I have some stock of quality 5w30 fully synthetic, long life diesel oil and would like to know if this oil would be ok to use, thanks.

Asked by: Trevor Smith  | 12.07am, Friday 11 April

WW says:

I do not know the recommended grade of oil for your engine, but you should be able to find a manual on line if you have not got one.
I think that most marine engine manufacturers do not recommend fully synthetic oil, but a high grade mineral oil instead. Synthetic oils were originally developed for racing cars, and are good in close tolerance engines as the polymer chains resist breaking up, they also give long service intervals which is why they are used in a lot of modern cars. Boat engines do not run in the same way as cars, and it is best to stick to the engine manufacturers recommended API grade oil.

Rupert Smedley  | 9.24AM, Friday 11 April

That sounds about right, the A2 refers to a min grading of API A2.

Rupert Smedley  | 10.20AM, Friday 11 April

Readers say:

Hi Rupert and thank you. I have just noticed that inside the front cover of the engine manual that the previous owner/service agent has written "Engine oil - 15w40 Mineral A2".

Trevor Smith  | 10.04AM, Friday 11 April

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