Maintaining your 2009 Ford FLEX with the 3.5L 6-cylinder engine requires precise fluid selection to ensure longevity and peak performance. This vehicle, equipped with the versatile 3.5L engine, relies on specific oil viscosities and fluid specifications to handle everything from daily commuting to heavy towing. Using the wrong lubricant can lead to premature wear, reduced fuel economy, and costly repairs. This guide details the exact AMSOIL products recommended for your FLEX, covering engine oil, filters, transmission fluid, and essential maintenance fluids.
Recommended AMSOIL Products
Ensuring your Ford FLEX receives the correct lubrication starts with choosing the right motor oil and filter combination. For this 3.5L engine, the required viscosity is 5W-20. Whether you seek maximum protection, extended service intervals, or an economy-friendly option, AMSOIL offers tailored solutions. Below are the specific products recommended for this vehicle, including the precise oil filters required to seal the deal.
Engine Oil Recommendations
The heart of your FLEX is the 3.5L engine. To protect it from wear and sludge while maximizing horsepower retention, start with a premium synthetic motor oil. The AMSOIL Signature Series 5W-20 100% Synthetic Motor Oil is the top choice for drivers who demand the highest level of protection. It provides 75% more engine protection against horsepower loss and wear compared to industry standards, making it ideal for high-stress driving, extreme temperatures, and extended drain intervals up to 25,000 miles.
If you prefer a balance of performance and value with a slightly shorter, yet still extended, service life, the AMSOIL Extended-Life 5W-20 100% Synthetic Motor Oil is an excellent alternative. This oil offers 37% more cleaning power to keep the engine running smoother and provides guaranteed protection for up to 20,000 miles between changes.
For those who need a fluid that performs like a conventional oil but with the benefits of synthetic technology at a budget-conscious price point, the AMSOIL OE 5W-20 100% Synthetic Motor Oil is designed to outperform conventional oils while meeting OEM mileage expectations. It features a 100% synthetic formulation that fights sludge and deposits, ensuring your engine stays clean. If your FLEX has accumulated over 75,000 miles, the AMSOIL 5W-20 100% Synthetic High-Mileage Motor Oil is specifically formulated with boosted detergents and anti-wear additives to help older engines last longer.
Oil Filter Recommendations
The oil filter is the guardian of your engine, removing contaminants that cause wear. The primary filter size for the 2009 Ford FLEX 3.5L is the EAO17. The AMSOIL Oil Filter is engineered to provide 99% filtration efficiency at 20 microns, with lower restriction than competing filters to keep parts lubricated. If you are looking for a cost-effective, OEM-compatible option, the WIX Oil Filter is a reliable choice. For premium performance with advanced media, the WIX XP Oil Filter offers improvements over standard OEM-branded filters.
Automatic Transmission Fluid
The 2009 Ford FLEX with the 3.5L engine typically utilizes a 6-speed automatic transmission (6F50). Maintaining this transmission is critical for smooth shifting and longevity. Ford often specifies automatic transmission fluid for the power steering system as well, making a versatile fluid choice valuable. The AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid withstands the rigors of heavy towing and elevated temperatures while remaining fluid in sub-zero conditions. For a more economical option that still offers full synthetic protection, the AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid is designed to protect against wear and resists sludge. Both the Signature Series Multi-Vehicle and OE Multi-Vehicle versions provide excellent protection for the transmission and can also serve as a high-quality power steering fluid for Ford specifications.
Coolant and Antifreeze
The cooling system on your FLEX requires a robust antifreeze to prevent overheating and corrosion. The capacity varies depending on the heater configuration, with the rear heater system requiring approximately 13.2 quarts and the standard system around 11.1 quarts. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is an ethylene glycol, 50/50 pre-mix formulation that protects cooling system metals, gaskets, and hoses for up to 150,000 miles or 5 years. For those who prefer to mix their own, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant offers concentrated protection that surpasses standard metallic corrosion standards.
Gear and Differential Lubricants
Your FLEX’s differentials and transfer case benefit from high-quality synthetic gear lube. The Power Transfer Unit (PTU) typically requires SAE 75W-140 synthetic lubricant, while the rear differential generally uses SAE 80W-90 meeting Ford specifications. The AMSOIL SEVERE GEAR® 75W-140 100% Synthetic Gear Lube is ideal for the transfer case, providing advanced protection against wear and controlling thermal runaway. For the rear differential, the AMSOIL SEVERE GEAR® 80W-90 100% Synthetic Gear Lube contains friction modifiers for limited-slip applications. If you require different weights for specific conditions, the SEVERE GEAR® 75W-90 and SEVERE GEAR® 75W-110 also provide robust protection against rust and corrosion.
Brake Fluid
Safety is paramount, and the braking system requires fluid with a high boiling point. The AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid provides excellent ABS and traction-control responsiveness. It maintains a stable viscosity over a wide temperature range, ensuring consistent braking performance in all conditions.
Air Filters and Fuel Additives
Clean air is essential for the 3.5L engine to breathe efficiently. The WIX Air Filter offers premium media that improves upon OEM filters. To maximize fuel economy and restore performance, the AMSOIL P.i.® Performance Improver Gasoline Additive is recommended. It restores up to 14% horsepower and cleans GDI fuel injectors to 100% flow rate after just one tank of treated fuel.
About the Vehicle
The 2009 Ford FLEX represents a unique chapter in Ford’s crossover lineup, blending the utility of a wagon with the presence of an SUV. Introduced as a concept in 2005 and launched for the 2009 model year, the FLEX was designed to compete in the growing segment of family haulers and luxury crossovers. It is built on the Ford CD3 platform, sharing its foundation with the Taurus sedan but offering a taller, more spacious profile.
Equipped with the 3.5L Ti-VCT V6 engine in this model, owners experience a balance of power and efficiency that was impressive for its time. This engine, often referred to as the Cyclone engine, delivers smooth power delivery suitable for both highway cruising and moderate towing. The FLEX is particularly known for its “Star Gazer” panoramic roof and a flexible interior configuration, often featuring a bench seat that could accommodate seven passengers comfortably. Its boxy design maximizes cargo space and headroom, making it a favorite for families, outdoor enthusiasts, and anyone needing versatile storage without sacrificing driving dynamics. While some owners might debate its styling compared to the sleek lines of competitors, the FLEX’s functional design and reliable mechanicals have garnered a loyal following among those who prioritize practicality and comfort on the road.