Engine Oil

[AJones]

This is a quote from the owner manual for my MerCruiser 350 Magnum EFI Gen + Tournament Ski engine.

"To help obtain optimum engine performance and to provide maximum, protection, we strongly recommend the use of Quicksilver 4-cycle Marine Engine Oil. If not available, a good grade, straight weight, detergent automotive oil of the correct viscosity, with an API classification of SG/CD II, may be used.

The chart below is a guide to crankcase oil selection. Oil filter should always be changed with oil.

In those areas where recommended straight weight oil is not available, a multi-viscosity 20W-40 (SG/CD II) or as a second but less preferable choice, 20W50 (SG/CD II) may be used.

IMPORTANT: The use of non-detergent oils, multi-viscosity oils (other than 20W-40 or 20W-50), low quality oils or oils which contain additives specifically are not recommended."

The chart mentioned above basically shows the temperature ranges for the oil weights above. 50 deg. F and above use 40W. 32 deg. to 50 deg. use 30W. Below 32 deg. Use 20W.

I've used Castrol Heavy Duty 40W in my engine since purchased new in 96 with no problems. I also use a regular ACDelco PF1218 filter.

[sloppy]

Brent, Ajones and you both bring up a good point. If you have a Mercury engine I would go exactly by their guidelines. I have an Indmar in mine. The manual reccomends 15w40 wilth an SJ/CG-4 grade. The viscosity in 15w40 or any multigrade gives properties like a 15 weight when cooler and 40 weight when hot. SAE30 is thicker when cool than 15w40 and thinner when hot. The reason many boat and car manufacturers went with a multiviscosity is to give better starting, and cold weather protection. The main wear and tear on is during starting and power changes. To be honest with you the reason I started changing my own oil is that the Marina I was docked at put SAE30 weight in there. I noticed that the oil pressure was extremely high until the boat was warmed up. The new 15w40 oils have SL/CI-4 grade which exceeds SJ/CG-4 standards. I wrote Indmar with some tecnical questions on Motor Oil. There product manager wrote me back and told me what I listed in the last post. I did not think about the possibility of others having engines besides Indmar in their boat. Sorry about that. I have an 01 Outback LS with a Indmar 350 EFI. I am going by those guidelines. Best of luck.

Sloppy