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Oil Viscosity


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Hit the 50 hour mark so I need to do an oil change. Prior to this I called the dealer to ask what they put in the engine so I could have a litre of the same oil with me if I needed to add a bit and they told me they are using 25W40.

Now I have gone through the indmar manual prior to my oil change and see they only recommend 15W40.

So whats up with that. Can I use 25W40 (it's mercruiser marine oil)?

If using 25W40 during the break in period does anyone think it would be detrimental to the break in or the life of the engine.

If the oil was to ever reach the add mark on the dipstick , how much oil do you think it would take to bring it up to the full mark on the dipstick ? Last time I checked, which was last time out before the oil change, it was above the add mark (about middle of operating range on dip stick) and I only got 2 1/2 litres out of the engine. Am I missing something here or was I that low on oil ?

Any opinions are welcome.

Thank you.

Monsoon engine by the way.

Edited by Black&Blue'Bu
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I would use a 15-40 per indmar specs. I am using Rotella T from wally world, but there are others that work well.

That is what I was thinking but based on dealers recommendation I already bought about $50.00 worth of 25W40 oil. Might have to see if I can return at least the oil I did not open.

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According to a mechanic who will never touch my boat again, "The velocity of all oil is the same". Fingerwag.gif

LOL. The velocity eh ? Don't blame you for not wanting to take it back to that guy.

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Amsoil Marine 10w40 for me along with an Amsoil Eao filter.

Seems different people use slightly different viscosities of oil than what Indmar suggests in their manual. Maybe it is not so important ? Dontknow.gif

Cougar: Why do you use a different viscosity, or is that what you are supposed to use in a 2006 model ?

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Update from Indmar.

Indmar has told me that 25W40 is fine to use. What they did say is that the viscosity is not that important as long as the oil meets the API specs.

Also they said that as long as the first number is 15 or higher and the second viscosity number is 40 or higher the oil should be fine. Won't void warranty.

Cougar1: Note that this does not jive with the oil viscosity you are using.

To the others: thanks for your opinions.

Edited by Black&Blue'Bu
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I recommend calling Indmar customer service. I called them for mine because I could not find the Penzoil they recommend for my 8.1 l and I was told that it was good that I called because they had updated their oil specs for my engine AND also the capacity. I was told to run high quality straight 40w marine oil and that instead of 8 quarts to run 10. And no I am not burning any oil.

I was glad I made the call.


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