2010-2017 Lincoln Navigator Brake Fluid Type and Flush Interval

By Core Brake Parts Tech Team — Circleville, OH warehouse

The 2010-2017 Lincoln Navigator was filled with either Ford DOT 3 (spec WSS-M6C65-A1) or Ford DOT 4 LV (spec WSS-M6C65-A2), depending on the model year and the printing of the owner's manual. The safe answer for every year in this range is a DOT 4 LV fluid that meets WSS-M6C65-A2, because Ford states that fluid may also be used in vehicles that specify the DOT 3 spec. Ford's own DOT 4 LV data sheet recommends changing it every three years, even though the Navigator owner's maintenance schedule only calls for inspections.

Below is exactly what each Lincoln manual we pulled says, how to check your own truck in ten seconds, and what to replace while the system is open.

What each Navigator owner's manual specifies

Ford changed the wording in the Capacities and Specifications chapter several times during this generation. Here is what the manuals themselves say:

We did not verify the 2011-2013 printings line by line, so treat those years the same way the 2016 manual tells owners to: read the brake reservoir cap. The 2016 manual says it directly, recommending DOT 3 or DOT 4 LV fluid meeting either Ford spec and telling the owner to refer to the brake reservoir cap for the proper fluid.

Every one of these manuals lists the capacity the same way: between the MIN and MAX marks on the reservoir. There is no published refill volume for a flush, so buy more fluid than you think you need. Running the reservoir dry during a bleed pulls air into the master cylinder and the ABS unit.

Why DOT 4 LV is the safe choice for all years

Ford's data sheet for Motorcraft DOT 4 LV High Performance Brake Fluid (PM-20, spec WSS-M6C65-A2) says it meets FMVSS 116 DOT 4 and ISO 4925 Class 6, and that it may be used to service Ford vehicles that specify WSS-M6C65-A1, which is the DOT 3 spec. The same sheet warns not to use it in vehicles that specify WSS-M6C65-A3 (DOT 5.1), which does not apply to this Navigator generation.

The difference shows up in the numbers. The federal brake fluid standard, FMVSS 116, sets these minimums:

Ford's DOT 4 LV sheet lists 260 C (500 F) dry and 170 C (338 F) wet, and a viscosity of 750 mm2/s maximum at -40 C. That low cold viscosity is what the LV stands for: the fluid moves quickly through the ABS and stability control valves in cold weather. On a three-ton SUV that tows, the higher wet boiling point is the part that matters most, because it is what keeps the pedal firm on a long downhill grade after the fluid has aged.

DOT 3 and DOT 4 are both glycol-based and are made to mix. Do not ever add DOT 5 silicone fluid, power steering fluid or any petroleum product to this reservoir. The Navigator manuals warn that contamination with water, dirt or petroleum products can damage the brake system and cause failure.

How often to flush a Navigator's brake fluid

The 2015 and 2017 Navigator scheduled maintenance charts do not list a timed brake fluid replacement. At every oil change interval they call for inspecting the brake pads, rotors, linings, hoses and parking brake, and the multi-point inspection includes checking the brake fluid level. The long-interval items are the engine air filter, coolant, spark plugs, and transmission, axle and transfer case fluids.

Ford's own fluid data sheet fills that gap: the recommended change-out interval for its DOT 4 LV fluid is every three years. That is the interval we recommend for any 2010-2017 Navigator, and sooner if the truck tows regularly or lives in a humid climate.

The reason is moisture. Glycol brake fluid absorbs water over time, which is why the wet boiling point exists as a separate rating and why FMVSS 116 requires every container to warn the user to keep it tightly closed to prevent moisture absorption. As water content rises, the boiling point drops toward the wet figure. You will not see it happen; you will feel it as a pedal that sinks or goes soft after repeated hard stops.

Signs the fluid or system needs attention

• Brake Fluid Level Low message - the manuals say this means the level is low and the brake system should be inspected immediately. A falling level usually means worn pads or a leak, not that it needs topping off.
• Red brake warning light with the parking brake released - on this generation the parking brake is a foot pedal released by a lever at the lower left of the dash. If the light stays on after release, Ford says it indicates low fluid or a brake system malfunction.
• Soft or sinking pedal - air, moisture-laden fluid, a leaking hose or line, or an internal master cylinder leak.
• Dark, cloudy fluid - fresh fluid is clear to light amber. Darkening means age and contamination; flush it.
• Fade when towing downhill - classic sign of fluid that has absorbed water and is boiling in the calipers.

Doing the flush and what to replace at the same time

A flush on a Navigator is a moderate DIY job: pull old fluid from the reservoir, then bleed each caliper starting with the one farthest from the master cylinder until clean fluid comes out, keeping the reservoir above MIN the whole time. Use only fluid from a sealed container, which the manual also calls for. If the pedal is still soft after a manual bleed, or if the ABS unit was run dry, the factory service procedure uses a scan tool to cycle the ABS valves, which is a job for a shop.

Because you are already opening every bleeder, this is the right time to handle these:

• Pads and rotors - if they are near the wear limit, do them first and flush last, so pushing the caliper pistons back does not force old fluid into the ABS unit. Our front and rear brake kit for the 2010-2017 Lincoln Navigator covers both axles in one box.
• Rubber brake hoses - cracked or swollen hoses cause a spongy pedal no flush will fix. See our brake hose selection.
• Seized bleeder screws or rusted hard lines - common on northern trucks. Replace them now rather than snapping one mid-bleed; see brake lines.
• Master cylinder - if the pedal slowly sinks at a stop with no external leak, the master cylinder is bypassing internally. Browse replacement master cylinders.

For everything else on the system, start at our brake parts catalog.

Frequently Asked Questions

Can I put DOT 4 LV in a Navigator that calls for DOT 3?

Yes. Ford's data sheet for its DOT 4 LV fluid (WSS-M6C65-A2) says it may be used to service Ford vehicles that specify the DOT 3 spec WSS-M6C65-A1. It exceeds DOT 3 on both boiling points.

Can I mix DOT 3 and DOT 4 in my Navigator?

They are both glycol-based and compatible, so topping off one with the other will not harm the system. For a flush, use one fluid throughout, and choose DOT 4 LV so the whole system carries the higher rating.

How do I know which fluid my Navigator came with?

Read the brake reservoir cap under the hood and the Capacities and Specifications chapter of your owner's manual. The 2016 manual tells owners to go by the reservoir cap.

Does the Navigator maintenance schedule include a brake fluid change?

The owner's schedules we reviewed list brake inspections at every oil change but no timed fluid replacement. Ford's DOT 4 LV data sheet recommends changing the fluid every three years, which is the interval we recommend.

Is it normal for the brake fluid level to drop?

A slow drop as the pads wear is normal, because the caliper pistons move out and hold more fluid. A sudden drop, or a low level with thick pads, means a leak that needs to be found before the truck is driven.

Can I use DOT 5 silicone fluid?

No. DOT 5 silicone is not listed for the Navigator and does not mix with glycol fluid. Ford also warns against using its DOT 4 LV product in vehicles that specify DOT 5.1, which this generation does not.

Sources

1. 2010 Lincoln Navigator Owner's Guide (Ford) - DOT 3 PM-1-C, WSS-M6C62-A or WSS-M6C65-A1, capacity between MIN and MAX
2. 2014 Lincoln Navigator Owner's Manual, March 2014 printing (Ford) - DOT 4 LV PM-20, WSS-M6C65-A2
3. 2015 Lincoln Navigator Owner's Manual, second printing (Ford) - DOT 3 PM-1-C WSS-M6C65-A1, maintenance schedule, warning messages, foot-pedal parking brake
4. 2016 Lincoln Navigator Owner's Manual, February 2016 printing (Ford) - DOT 3 or DOT 4 LV, refer to reservoir cap
5. 2017 Lincoln Navigator Owner's Manual, April 2016 printing (Ford) - DOT 4 LV PM-20 WSS-M6C65-A2, sealed-container warning, maintenance schedule
6. Motorcraft DOT 4 LV High Performance Brake Fluid data sheet (Ford) - boiling points, viscosity, DOT 3 back-compatibility, three-year change interval
7. 49 CFR 571.116, FMVSS 116 Motor Vehicle Brake Fluids - DOT 3 and DOT 4 minimum boiling points, viscosity limits, moisture labeling