What weight of Mercruiser Quicksilver oil?

[glastron86]

I just bought my '86 Glastron last year. It has a 170hp Mercruiser and I had the dealership close by winterize it last year. They supposedly changed the oil. I have been checking the oil and after a while it got to where it needed a quart. I went in and asked them for one and they gave me some 25-40 Quicksilver oil. When I got home I decided to check the manual for my merc and it said to never use a multi-viscosity oil in this motor. So I took it back to the dealer and they said that this was wrong and this had to be the oil to use because it was the only weight of oil that Mercruiser made?! Now I need some help with this! I am new to all of this so I haven't necessarily learned who to trust yet. There are alot of people on here who seem to have alot of great knowledge so I am counting on that. Thanks for any help that anyone can give me!

 

[barts5oh]

Re: What weight of Mercruiser Quicksilver oil?

The manuals specify single weight oils due to the fact that the engines run at high rpm most of the time, unlike automobiles. The oils available back when your motor was new were relatively "crude" (no pun intended) compared with today's motor oils. The 25-40W looks like a good weight for your engine and if it's Quicksilver, it's meant for an I/O. In my Mercruiser, I'll be using a single weight synthetic racing oil, but your's is sufficient.

 

[Don S]

Re: What weight of Mercruiser Quicksilver oil?

 

[glastron86]

Re: What weight of Mercruiser Quicksilver oil?

Thanks for the help, and especially the service update Don! That makes me feel alot better about my dealership! I was beginning to worry about whether they should be doing the work on my boat or not.

 

[180shabah]

Re: What weight of Mercruiser Quicksilver oil?

You dealership did you right, your manual is more than 2 decades old. Alot of changes in that time.