what weight oil should I use in my 3.0

[dbok1]

I have a 2001 VIP with a 135 hp 3.0 4 cyl. I changed the oil last summer and got oil and a filter from the dealer and he said to not use motoroil. I did use the oil and filter he gave me, it seemed very thick. 20w-40 or 50?

Now, whenever I start my boat, it knocks for about 2 minutes until the oil gets flowing, or so I think. It seems that after it gets warmed up the knocking goes way away and it is fine the rest of the day.

I can't imagine the knocking is good for it, anyone have any suggestions on what weight oil to use or synthetic? Does synthetic break down as fast as other oils?

 

[Don S]

Re: what weight oil should I use in my 3.0

In this forum, we need to know if you have a Mercruiser or a Volvo, the boat manufacturer has nothing to do with it at all.
I will assume you have a Mercruiser so read this service bulletin from Mercruiser, if you should own a Volvo, their recommendations are almost identical. The oil recommended WILL NOT cause the engine to knock, or lifters to rattle when cold. That is a problem if that is what it is. Are you sure the engine doesn't vibrate a lot and something is rattling???

 

[Robj]

Re: what weight oil should I use in my 3.0

Is the noise an actual knock or just piston slap? If it goes away when the engine warms up, it may be piston slap. What I would do is use the oil as per Don's recommendations and just keep an eye on the problem. Piston slap is more of a nuisance than anything else, as long as it goes away when warm and does not get any worse. It should not affect your engines performance. At this point, based on the description of your problem, if it is just piston slap, it does not warrant trying to repair it because the only way to fix it is by rebuilding the engine.

Have a great day,

Rob.

 

[dbok1]

Re: what weight oil should I use in my 3.0

sorry guys, it is a mercruiser

it could be piston slap, i did not think about that. Yes, after it is warm, within 30 seconds to 2 minutes it goes away and I do not here it the rest of the day. I just hear it on start up first thing in the morning or if it has been sitting for a long time (4+ hours) while we are tied up, etc. I did not hear it the first season i used the boat, but when i changed the oil that winter i heard it the next summer and this summer. I di dnot change the oil yet this summer because of a break down that was irrevelant to this problem and bad weather.