Can someone tell me which oil to use for a 4.3L MPI. Need a a viscosity that can be purchased at an auto parts store. Buddy of mine bought a deck boat with no manuals.

Also, can someone provide a crossover Wix or equivalent oil filter? The Merc number is 35-866340K01.

I could not read the fuel/water sep number but if anyone has an auto part store equivalent I would appreciate it.



Thanks,

Tom

A 10w-40 would be a good application. I couldn't cross that number that you have, but you should be able to find a filter pretty easily. An oil such as this would be really good.............

http://www.amsoil.com/StoreFront/wcf.aspx

OReilly auto had all the crossover part numbers. Put straight 40W oil which is what I run in my blue motors.

You're better off with a multi viscosity oil such as a 10w-40 as opposed to a straight weight oil. The multi viscosity will flow to the top end of your motors quicker on startup, therefore better volume flow and better lubrication. After it is heated it still will protect the same as a straight weight.

Yeah but not 10W40.

Why wouldn't a 10w-40 be good, its the same thing as a straight 40. It just has a lower cold pour point temp. Whether it is a 0w-40, 5w-40, 10w-40, 15w-40, 20w-40, 25w-40 or straight 40, they are still a 40 weight protection, some just get to the top end quicker than others.

Finally googled the right jargon. From Mercruiser website FAQ's:


What type of oil should I use? Can I use synthetic oil?
Engine Oil

To help obtain optimum engine performance and to provide maximum protection, we strongly recommend the use of the following oils listed in the order of recommendation:

MerCruiser / Quicksilver Synthetic Blend, NMMA FC-W rated, 4 cycle oil.
MerCruiser / Quicksilver 25W40 NMMA FC-W rated oil.
A NMMA FC-W rated oil.
MerCruiser / Quicksilver 4-cycle 25W40, non FC-W rated oil.
A good grade straight weight detergent automotive oil per the operating chart below.

NOTE: The use of non-detergent oils, multi-viscosity oils (other than as specified), non-FC-W rated synthetic oils, low quality oils or oils that contain solid additives are specifically not recommended.

So, any -40 weight will work, according to them. And of course Mercury Oil is listed first, so they can make another dime off of their customers.

Agreed, I put 40W from the auto parts store. I run Valvoline 40W Racing in my modified carb 500 HP's and never had a problem. La is hot though. May not be the best oil for ice fishing in Michigan.