What type oil is best for 1997 mercury 150 outboard motor?

Answer 1

Assuming you are talking about a two cycle, Mercury V-6, either carburetor or fuel injection. Four-Cycle -- just use Mercury or Quicksilver brand 4cycle Outboard oil.

The outboard oil is particularly formulated to be tolerant of some of the traits of outboards, including exposure to high- humidity.



for your two cycle Mercury
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the best oil to use for your Mercury outboard is Mercury brand Premium Plus two-cycle oil. Second it Mercury Premium two cycle, sold at Mercury dealers. the identical oils are available in Quicksilver (Mercury) brand at retailers.

If your motor still has the oil tank and auto-oiling system just add it there. Some engine overhaulers/rebuilders remove the Mercury oiling system. In that case mix the oil into the fuel at 50 parts gasoline to one part oil. (50:1) This is about 1 pint per six gallons, 1 quart per 12 gallons.

Next choice is any other engine makers brand, Yamaha, Johnson/Evinrude, Tohatsu/Nissan-- so long as it is (of course) the two-cycle TCW-3 rating.

Next choice is a TCW-3 CERTIFIED oil. There are some that claim to be equivalent, but they do not get it tested or certified. Why not? So use only brands with the NMMA Certification label. There are actually many brands. Some of the longest in the business is Exxon (old time Esso) and Texaco. I do trust those in a pinch, along with Irving which is available in the Northeast. But since Quicksilver is available in most Walmart stores and at 40 percent discount at Sam's Club, it should be pretty easy to always have a good oil on hand.

It is my understanding that the engine makers oils generally exceed the standards. Any oil that is certified at least meets it. Anti-carbon chemistry can be improved by using an addtive such as: Bombardier Carbon Guard, Yamaha Ring Free, or Mercury/Quicksilver Quikleen. All are similar and add the key ingredient 2-butoxy-ethanol solvent/detergent to the fuel system. This ingredient system is already present at high levels in the premium oils form Yamaha, Bombardier and Mercury.

My experience is to use the engine-makers brand oil. I have never had a powerhead failure. One of my motors was a 1964 Mercury 85 hp Six Cylinder, used every year in salt water until 2005. I gave it up because I was tired of dealing with the dual point ignition system, newer motors have electronics.

My sister bought a 1978 Boston Whaler which had its original 1978 Johnson 200 hp V6. She told me it started hard that first summer (1995). In the fall I pulled the plugs. they were the wrong kind (bad sign) and one cylinder the electrode was bent in to short it out completely (real bad sign). Pulled the head and the stuck ring had torn the top of the piston off. All cylinders had stuck rings, scored cyclinders, and scored and burned pistions. The ring lands (grooves) were solid with brown, sticky asphalt, just like off the roadway. Well, I had to bore it .030 over all around, and 6 new pistons. From then on it was run on Quicksilver oil. the previous owner had left several cases of an unrated two cycle oil in the boat, and told my sister he got a heck of a deal on it.

Details on the TCW-3 standard tests are here. It is not trivial.
http://www.nmma.org/certification/local/downloads/documents/TCW3_ProductApprovalSystem.pdf

A listing of the Brand Names and makers of Certified Oils can be found here:
http://www.nmma.org/certification/programs/oils/

There is an excel file posted that lists the current products.
http://www.nmma.org/certification/local/downloads/documents/TC-W3-2009.xlsx

Some people will tell you that a particular synthetic is great, or a high-performance oil (some are even available from the Engine Makers like Mercury Racing) is fantastic. The point is these are special high performance, expensive, and usually used at higher mix ratios than recreational engines. Racers often run at 7,000 RPM on up, often run much hotter, and the strong mix ratios like 25 to 1 or even stronger mean they are formulated with other additives and dilution aids. Such a mixture leans out your fuel, and requires different jetting or injection calibration. Stick with the standard Engine maker oils for recreational use.