Quicksilver Blog

Maintenance Tips for Mercury OptiMax Outboards

There are many Mercury® OptiMax® outboard engines on the water, and if you own one of the 3.0-liter V6 Pro XS® models and love it, some basic maintenance and preventive care can help you keep it running strong.

OptiMax motors are a two-stroke design with direct fuel injection (DFI) that uses compressed air to inject a highly atomized fog of fuel directly into the combustion chamber. The result is outstanding power delivery with minimal exhaust emissions.

The Quicksilver® marine engine experts offer these tips for do-it-yourself owners intent on enjoying any 3.0-liter Mercury OptiMax outboard for many seasons to come.


Perform Maintenance By the Book

If you are not already doing so, follow to the letter the maintenance schedule as prescribed in the owner’s manual for your OptiMax engine. Regular maintenance is the best way to head off reliability issues and expensive repairs, and with a basic tool set and quality Quicksilver parts, you can accomplish most tasks yourself. If you do not have the owner’s manual for your Mercury outboard, you can download a PDF version or order a printed copy directly from Mercury Marine, or from a Mercury Authorized Dealer.

The Right Oil is Critical

Per the owner’s manual, Quicksilver Synthetic Blend Performance DFI 2-Stroke Outboard Oil is recommended for use in OptiMax outboards. In fact, the manual also states that “Severe engine damage may result from use of an inferior oil.” Quicksilver DFI oil is specifically formulated to meet the requirements of the OptiMax DFI two-stroke engine, and will help minimize piston scuffing and the formation of performance-robbing carbon deposits in the combustion chamber. Quicksilver DFI oil outperforms other oils by combining a carefully modified base stock blend with a synthetic additive package. This is a premium oil designed specifically for your OptiMax outboard.

Treat Your Fuel Right

The OptiMax DFI fuel injectors are located in the cylinder heads, with the injector outlets within the combustion chamber. To maintain performance and reliability it is important to prevent carbon deposits from forming on the small injector pintle, the actual nozzle that opens and closes to control the flow of fuel. It’s recommend to add Quickleen® Engine & Fuel System Cleaner to the engine's fuel at each fill-up. Quickleen is a deep-cleaning fuel treatment formulated to thoroughly remove carbon deposits from fuel injectors, spark plugs, piston crowns and cylinder heads. Follow the instructions on the bottle. Using more than the recommended amount will not improve additive performance. Quickleen is part of the complete Quicksilver Fuel Care System, formulated to be your best solution for heading off fuel-related problems. Each additive is highly concentrated for convenient use in large-capacity boat fuel tanks.

Get This Tool

Replacing the fuel filter is part of the annual/100-hour OptiMax outboard maintenance routine. The filter cap is located on top of the vapor separator tank (VST) on the port side (left side) of the powerhead. The top of the filter has a plastic castellated cap, and while it’s possible to use the shaft of a screwdriver to turn this cap, doing so risks breaking the plastic tabs, as the filter can be very tight. If those tabs break it can be very difficult to remove the filter. Instead, pick up the Quicksilver Fuel Filter Tool (p.n. 91‑896661) from a Quicksilver dealer or retailer. It’s shaped to fit on the castellated cap and applies equal pressure to those tabs when you turn it with your 3/8-inch ratchet. Also use the tool to install a new OEM-quality Quicksilver fuel filter. Apply a little engine oil or Quicksilver 2-4-C Marine Grease to both filter O-rings before installing the new filter. Follow owner’s manual instructions on replacing the filter and draining the VST of any accumulated water.


With a little maintenance and the right tools, you can enjoy the power and performance of your Mercury OptiMax outboard for many years of on-water fun.