AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid
AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is a multi-spec, glycol-ether hydraulic fluid for passenger cars, light trucks, and powersports vehicles that call for DOT 3, DOT 4, or DOT 5.1. The formula meets and exceeds the FMVSS 116 boiling-point and viscosity requirements for all three specifications in a single bottle.
Ultra-high dry and wet boiling points
Brake fluid lives or dies on boiling-point margin. Under hard, repeated braking, caliper fluid temperatures can climb fast enough to vaporize lower-grade fluid, producing a soft pedal known as vapor lock. AMSOIL DOT 3 and DOT 4 Synthetic Brake Fluid posts a dry equilibrium reflux boiling point of 271 C (520 F) and a wet ERBP of 187 C (368 F), comfortably above the DOT 3 minimums of 205 C dry and 140 C wet, the DOT 4 minimums of 230 C dry and 155 C wet, and the DOT 5.1 minimums of 260 C dry and 180 C wet. The wet figure is measured after the fluid has absorbed 3.7 percent water by weight, simulating years of in-service moisture pickup. A nitrogen blanket is added during manufacturing to purge atmospheric moisture before the cap is sealed, which keeps fresh fluid genuinely dry at the moment a technician opens it.
Fights water contamination across the brake system
Glycol-ether brake fluid is hygroscopic, meaning it attracts and binds water molecules. Moisture seeps in through microscopic pores in flexible brake hoses, past seals, and through the master cylinder cap. Once water enters the loop, it drops the boiling point, corrodes steel lines and caliper bores, and degrades EPDM rubber seals. The high wet ERBP preserves stopping performance through normal service-interval moisture pickup, while corrosion inhibitors protect cast-iron, aluminum, copper, brass, and steel components in modern hydraulic brake hardware.
Maximum ABS and traction-control responsiveness
Modern vehicles cycle brake fluid through fast-acting ABS, ESC, and traction-control solenoids that depend on consistent fluid flow at sub-zero temperatures. AMSOIL DOT 3 and DOT 4 Synthetic Brake Fluid carries a low-temperature viscosity of 817 cSt at -40 C (-40 F), well under the DOT 3 maximum of 1,500 cSt and the DOT 4 maximum of 1,800 cSt, and inside the tighter DOT 5.1 ceiling of 900 cSt. Lower cold-weather viscosity helps ABS and stability-control units pulse and release pressure cleanly in winter conditions, which translates to firmer pedal feel during a cold-weather panic stop.
Stable viscosity from cold start to track heat
The formula holds a high-temperature viscosity of 2.0 cSt at 100 C (212 F), keeping the fluid thick enough to lubricate caliper pistons and master cylinder bores after a long descent or a string of heavy stops. Paired with the low -40 C figure, the range delivers consistent pedal feel across the operating envelope of most passenger and powersports brake systems.
Built for cars, light trucks, and powersports
Because the fluid carries DOT 3, DOT 4, and DOT 5.1 performance simultaneously, it covers most domestic, Asian, and European cars, pickups, SUVs, and crossovers, plus motorcycles, ATVs, UTVs, snowmobiles, and personal watercraft that specify polyglycol DOT 3 or DOT 4. It also suits clutch hydraulic systems calling for the same classifications. It is not compatible with DOT 5 silicone brake fluid and must not be mixed with DOT 5.
Recommended applications and service intervals
Pour AMSOIL DOT 3 and DOT 4 Synthetic Brake Fluid into any passenger car, light truck, or powersports application that calls for DOT 3, DOT 4, or DOT 5.1. To match the right product and the exact DOT classification listed on the master cylinder cap, work through the AMSOIL vehicle lookup guide.
- Normal passenger and light-truck service: change the fluid every two years for maximum performance, or sooner if the bulletin in the owner manual specifies a tighter interval.
- Severe service, including frequent towing, mountain driving, track days, and powersports riding: flush at the shorter end of the two-year window and inspect color and moisture readings annually.
- Racing applications running a DOT 4 specification: use AMSOIL DOMINATOR DOT 4 Synthetic Racing Brake Fluid, which carries a higher dry and wet boiling-point profile for sustained high-temperature racing.
- Outside the United States: this product is not available in Canada.
Do not mix this fluid with DOT 5 silicone. When flushing contaminated fluid, bleed at all four wheels until clear fluid runs from each bleeder, and keep the master cylinder reservoir topped off to prevent introducing air into the ABS module.
Typical technical properties
| Property | Value |
|---|
| Dry equilibrium reflux boiling point | 271 C (520 F) |
| Wet equilibrium reflux boiling point | 187 C (368 F) |
| Viscosity at -40 C (-40 F), cSt | 817.0 |
| Viscosity at 100 C (212 F), cSt | 2.0 |
| DOT 3 specification, dry ERBP minimum | 205 C (401 F) |
| DOT 4 specification, dry ERBP minimum | 230 C (446 F) |
| DOT 5.1 specification, dry ERBP minimum | 260 C (500 F) |
| DOT 3 wet ERBP minimum | 140 C (284 F) |
| DOT 4 wet ERBP minimum | 155 C (311 F) |
| DOT 5.1 wet ERBP minimum | 180 C (356 F) |
Order AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid
AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is stocked in the 12 oz. bottle (BFLVCN-EA) and the 12 oz. case of 12 (BFLVCN-CA), and is backed by the AMSOIL Limited Liability Warranty. For product-match context across cars, light trucks, and powersports, see the AMSOIL vehicle lookup guide and the AMSOIL car oil guide, then place the order: Order Now.
Customer reviews
Indian
Just changed the break Fluid in my Indian Springfield with Amsoil. First time using Amsoil break fluid. worked very well, have put about 300 miles on the bike since the change. Brakes are working very well.
By Joe from Northeast Georgia on July 11, 2026.
Would recommend this to a friend.
Great
needed this to just have some extra on hand and for when I do break fluid change out here someday. Really like Amsoil products and service and shipping is great!
By Snowman from Yakima WA on May 30, 2026.
Would recommend this to a friend.
Best brake fluid
I flushed out my brake system on three vehicles, and now the brake pedal is much more responsive on all vehicles.
By Freddy from North Carolina on May 15, 2026.
Would recommend this to a friend.
Read all 108 reviews
Frequently asked questions
What is the difference between DOT 3, DOT 4, and DOT 5.1 brake fluid?
All three are glycol-ether based hydraulic brake fluids governed by FMVSS 116. The main differences are the minimum dry and wet boiling points and the maximum cold-temperature viscosity. DOT 4 raises the boiling-point bar over DOT 3, and DOT 5.1 raises it further and tightens the cold viscosity limit. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid meets and exceeds all three specifications, so a vehicle that calls for any of DOT 3, DOT 4, or DOT 5.1 is covered by this single bottle.
Can DOT 3 and DOT 4 brake fluid be mixed in the same system?
Yes. DOT 3, DOT 4, and DOT 5.1 are all polyglycol fluids and are chemically compatible with one another. Topping up a DOT 3 system with this fluid is allowed, and the higher boiling-point margin of the new fluid carries through to the mixture. For best results during a planned service, perform a full flush rather than a top-off so the entire system runs on a single, known fluid.
Is this fluid compatible with DOT 5 silicone brake fluid?
No. DOT 5 is a silicone-based fluid and is not compatible with polyglycol fluids like DOT 3, DOT 4, and DOT 5.1. Do not mix this product with DOT 5. If the master cylinder cap or owner manual specifies DOT 5 silicone, use a DOT 5 silicone product instead.
How often should brake fluid be replaced?
Change the fluid every two years for maximum performance under normal service. Glycol-ether brake fluid absorbs moisture from the atmosphere over time, which lowers the wet boiling point and accelerates internal corrosion. Severe service, track use, and humid climates can shorten the practical interval, so the manufacturer's published interval and the two-year mark should both be respected, whichever comes first.
Will this work for a clutch hydraulic system?
Yes, when the clutch master and slave cylinder are designed for DOT 3, DOT 4, or DOT 5.1 polyglycol fluid. Many vehicles that share the brake reservoir with the clutch circuit, or run a dedicated clutch reservoir, specify the same DOT class as the brake system. Verify the requirement on the reservoir cap or in the owner manual before filling.
Is this brake fluid available in Canada?
No. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid (BFLV) is not available in Canada. Canadian customers should select a regionally stocked AMSOIL brake fluid product instead.
Does this brake fluid back the AMSOIL Limited Warranty?
Yes. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is backed by the AMSOIL Limited Liability Warranty. Use the product in applications that specify a DOT 3, DOT 4, or DOT 5.1 polyglycol brake fluid, follow the recommended change interval, and keep the bottle sealed and out of reach of children until use.
