AMSOIL Synthetic-Blend 25W-40 Marine OilAMSOIL has released a brand new 25W-40 4-stroke marine engine oil for Mercury engines and we have it available for immediate delivery. The new AMSOIL Synthetic-Blend 25W-40 Marine Oil (product code: WCM) will be suitable for any Mercury Marine outboard, stern drive or inboard engine that requires a 25W-40 motor oil. This new 25W-40 meets the NMMA “FC-W Catalyst Compatible” specification, but is also suitable for engines that are not equipped with a catalyst.

Why Did AMSOIL Make A 25W-40?

In the past, AMSOIL had suggested their Synthetic 10W-40 Marine Motor Oil for Mercury and Mercruiser engines that required 25W-40 oil. As we explained in this article, AMSOIL’s 10W-40 Synthetic Marine Oil is a highly capable and safe option that can easily replace Mercury 25W-40. The problem is that many consumers simply will not consider a 10W-40 product when they are looking for a 25W-40. This is especially true if they have warranty concerns. A 25W-40 would be the quick and safe choice for busy consumers, so it only makes sense for AMSOIL to have a Mercury-specific 25W-40 ready to go.

Why A Semi-Synthetic 25W-40?

With AMSOIL being almost exclusively a synthetic oil company, why would this product be a synthetic-blend? Mercury Marine owner’s manuals specifically suggest the use of only semi-synthetic 25W-40 motor oil for many of their engines. To alleviate any warranty concerns, AMSOIL opted to make this product a semi-synthetic.

Mercury does not specify why a full synthetic oil is not suitable for their engines and frankly we don’t believe that there is a legitimate reason. We don’t know of any application where a full synthetic oil would be anything but a benefit. Our suspicion is that Mercury felt that a synthetic-blend oil would be an adequate product that met a reasonable price point. We don’t think there is a justifiable mechanical reason behind this logic.

AMSOIL’s Technical Department has always suggested a full synthetic oil for Mercury Marine engines. But in the case of this new 25W-40, rather than reinvent the wheel for consumers, they felt that a high-quality semi-synthetic 25W-40 oil would provide great service and be a viable choice for the average Mercury engine oil shopper.

Features and Benefits Of AMSOIL Synthetic-Blend 25W-40 Marine Oil

  • Robust anti-wear protection
  • Powerful anti-rust and corrosion protection
  • Suitable for catalyst and non-catalyst equipped engines
  • Outstanding shear resistance
  • Does not contain viscosity index improvers
  • Protects during heavy loads and high operating temps

How Is AMSOIL Synthetic-Blend 25W-40 Marine Oil Priced?

AMSOIL has priced this new 25W-40 priced similarly to the OEM Mercury Synthetic-Blend SAE 25W-40 Marine Engine Oil. We will submit that AMSOIL made a point of making a superior oil too. Check out our wholesale buying options for individuals or businesses. Request a wholesale price list with the form on this page and see how our high quality products are a great value.

Where to Buy How to Buy AMSOIL Synthetic-Blend 25W-40 Marine Oil? can ship this new 25W-40 for Mercury Marine engines from Mississauga in Eastern Canada and Edmonton in Western Canada. We also ship from 11 warehouses in the United States. We can have a case of this new oil on your doorstep in just a day or two.

Can This New 25W-40 Be Used In Flat Tappet Cam Engines?

We would not suggest this new 25W-40 for older Mercruiser engines with flat tappet cam shafts. Some older Mercruiser engines such as the 5.7L (350 c.i.) produced by General Motors had flat tappet camshafts. Flat tappet cams require an engine oil with very high zinc levels. As this new 25W-40 oil is suitable for engines with catalytic converters, it will not have the zinc levels needed. High zinc levels are not compatible with catalytic converters. We offer a motor oil suggestion for flat tappet cam Mercruiser engines in this article.

The same logic applies to automotive motor oils. The latest passenger car motor oils do not contain enough zinc to protect older engines with flat tappet cams.

Other Oils Replaced By AMSOIL Synthetic-Blend 25W-40 Marine Oil

AMSOIL Synthetic-Blend 25W-40 Marine Oil is a high-quality substitute for the following marine engine oils.

  • Mercury Synthetic-Blend SAE 25W-40 Marine Engine Oil
  • Quicksilver 25W-40 4-Stroke Synthetic Blend Marine Engine Oil
  • Quicksilver 25W-40 4-Stroke Mineral Marine Engine Oil
  • Bel-Ray Marine 4-Stroke 25W-40 Engine Oil
  • Cabela’s Signature Semi-Synthetic 25W-40 4-Cycle Oil
  • Lucas Stern Drive 25W-40 Inboard Engine Oil
  • Sierra 25W-40 Premium Blend 4-Stroke Marine Oil
  • Sierra 25W-40 Synthetic Blend 4-Stroke Marine Oil
  • Sierra 25W-40 Premium Blend Catalyst Compatible 4-Stroke Marine Oil
  • Starbrite Premium Synthetic Blend 25W-40 4-Stroke Engine Oil
  • West Marine Premium 4-Stroke Synthetic Blend 25W-40 Outboard Oil

AMSOIL Synthetic 10W-30/SAE 30 Diesel OilA reader asks: We have two ZF 301 marine transmissions and the current transmission oil is getting very hot. We would like to try an AMSOIL synthetic oil for this application. What have you got there?

Our answer: According to our research, your transmissions call for a straight-grade SAE 30 engine oil meeting any of these common motor oil specifications.

  • API CD/CE/CF-4/CF/CG-4/CH-4/CI-4
  • ACEA A/B/E

We do offer one particular product that covers these specifications and qualifies as a “straight grade” SAE 30 motor oil. AMSOIL Synthetic 10W-30/SAE 30 Heavy Duty Diesel Oil is considered to be a straight-grade SAE 30. Here’s why this full synthetic SAE30 engine oil would be a great candidate for your ZF marine transmission.

  • Shear stable, maintains viscosity
  • Full synthetic formula reduces friction for cooler operation
  • Low volatility, will not boil-off when exposed to extreme heat
  • Resists deposit formation
  • Provides powerful wear control
  • Optimizes power transfer and efficiency
  • Designed for long service life
  • A true all-climate straight SAE 30 oil

Oildepot can offer AMSOIL Synthetic 10W-30/SAE 30 Heavy Duty Diesel Oil for ZF Marine transmission use for US or Canadian customers. Contact us using the form on this page or call us at 1-800-748-5781 for wholesale prices.

AMSOIL Series 600 DOT 4 Synthetic Racing Brake FluidA reader asks: I would like to buy AMSOIL DOT 4 Brake Fluid. I live in Canada, but it seems as though nobody carries it up here. Do you sell it? Also can Dot 4 brake fluid replace DOT 3 if I flush out all of the old fluid ?

Our answer: Unfortunately the AMSOIL DOT 4 Brake Fluid is no longer imported into Canada. AMSOIL will not ship it to Canada, so the only possible way to attain it is to pick it up from a US address. It would probably be more feasible to buy a competing DOT 4 product in Canada. Motorcycle dealers are a great place to check as they generally carry a selection of high quality DOT 4 brake fluids.

For US residents, we certainly can sell AMSOIL DOT 4 Brake Fluid as it is shipped directly from a US warehouse.

As for replacing your old fluid, DOT 4 can replace DOT 3 brake fluid, but DOT 3 cannot replace DOT 4. Without knowing the particulars of the current brake fluid or replacement product, it wouldn’t hurt to contact the manufacturer of the replacement fluid to verify the compatibility.

AMSOIL Synthetic Dirt Bike 10W-50 OilA reader asks: I have a 2012 KTM 990 Adventure that specifies a ridiculously expensive Motorex full synthetic oil. Does Motorex have additives specifically for some coating or other materials in the 990 engine? Do you have any feedback on using an AMSOIL product in this engine? I’m concerned about veering from the OEM oil in case the wear rate increases and longevity suffers.

Our answer: There is absolutely nothing special about the formulation of Motorex motorcycle oil that is specific to KTM motorcycles. Motorex just happens to be the factory fill and has had a relationship with KTM for many years. The recommended oil for your 990 Adventure is either a 5W-40 or 10W-50 motorcycle oil covering the JASO MA specification. We would recommend the professional-grade AMSOIL Dirt Bike Synthetic 10W-50 Oil as a high-powered substitute for Motorex Cross Power 4T 10W-50.

AMSOIL Dirt Bike 10W-50 possesses a wide variety of attributes that make it the ideal choice for KTM motorcycles.

  • Delivers the ultimate in wear protection
  • Resists shearing down in extreme heat
  • Reduces friction for maximum output
  • Combats clutch slippage and fade for maximum plate life
  • Provides smooth gear shifting
  • Flows exceptionally well during cold starts

We can assure you that AMSOIL Dirt Bike Synthetic 10W-50 will offer world-class performance and protection for your KTM engine and transmission. It will most definitely not be a step down from Motorex.

AMSOIL Dominator Coolant BoostAMSOIL has revised the formula of their popular Dominator Coolant Boost product. This coolant additive now employs an ultra-sophisticated organic acid technology (also called “OAT”) which has improved the product’s temperature reduction abilities and provides even quicker motor warm-up times in winter. Dominator Coolant Boost now delivers heat reduction that is among the best in the industry when used with either straight water or in conjunction with antifreeze. The new formula also lasts longer and is universally compatible with all water and antifreeze types.

What Is AMSOIL Dominator Coolant Boost?

Dominator Coolant Boost is a supplemental additive for antifreeze or straight water in regular automotive engines or racing cars. Dominator Coolant Boost lowers coolant temperatures, helps engines warm-up faster in winter and fights cooling system corrosion.

How Does Dominator Coolant Boost Work?

Dominator Coolant Boost acts as a surfactant to improve the heat transfer capabilities of the coolant. The enhanced surface tension of the treated coolant provides improved contact with metal surfaces and consistent performance throughout the coolant system. Unlike competing coolant conditioners, Dominator Coolant Boost doesn’t just provide improved cooling system performance in extreme heat. The AMSOIL surfactant technology also reduces engine warm-up times by up to 54%. Lastly, Dominator Coolant Boost contains powerful corrosion inhibitors that protect steel, copper, brass, aluminum, solder and all other cooling system materials.

Why Did AMSOIL Reformulate Dominator Coolant Boost?

The coolant additive market is very competitive and as AMSOIL doesn’t like to take a back seat to anyone, they improved the product and upped the ante. AMSOIL Dominator Coolant Boost delivers a temperature reduction of up to 25°F (mixed with straight-water). Here’s how the competitions stacks up.

  • Royal Purple Purple Ice (22°F reduction)
  • Red Line Water Wetter (20°F reduction)
  • Lucas Super Coolant (20°F reduction)

Why Is A Coolant Additive Needed?

When used with antifreeze mix, Dominator Coolant Boost delivers a surfactant boost that lasts about 50,000km (30,000 miles). When it comes to straight water, Dominator Coolant Boost offers much better cooling and anti-corrosion properties that water simply does not possess.

Where Can I Buy AMSOIL Dominator Coolant Boost?

Oildepot sells AMSOIL Dominator Coolant Boost in Canada and the United States. Contact us using the form on this page or call us at 1-800-748-5781.