AMSOIL Signature Series ULV 100% Synthetic Automatic Transmission Fluid

Product overview

Ultra-low-viscosity fluid exists because eight, nine, and ten-speed transmissions need oil that moves through tight passages quickly enough to keep shift timing precise. Signature Series ULV ATF is built for the transmissions that specify it.

At 4.5 cSt at 100°C it is the thinnest automatic transmission fluid AMSOIL makes, and it carries the same Signature Series additive treatment for wear protection and heat resistance. Use it only where an ultra-low-viscosity fluid is called for.

What the formula does

• High concentrations of antioxidants make the formula naturally heat resistant, which is what holds off the sludge and varnish that clog narrow passages.
• The Signature Series line is built around that heat resistance. In AMSOIL's 180,000-mile severe-service taxi trial, the Signature Series Multi-Vehicle formula still held 83 percent of its original oxidation inhibitors.
• Low viscosity reduces internal drag, which is why manufacturers specify an ultra-low-viscosity fluid in newer multi-speed automatics.

MERCON ULV and DEXRON ULV are their own requirements

Signature Series ULV ATF is listed for two requirements: Ford MERCON ULV and GM DEXRON ULV. Those are not lighter versions of MERCON LV or DEXRON VI, and a transmission built around one of them is not served by a fluid that meets a different specification in the same family.

Viscosity shows the gap quickly. This fluid is 4.5 cSt at 100°C, Signature Series Fuel-Efficient ATF is 6.3 cSt, and the conventional multi-vehicle grade is 7.5 cSt. Confirm the requirement published for the transmission before ordering, because the three grades are matched to different application lists.

Cold-temperature flow in an ultra-thin fluid

Cold, thick automatic transmission fluid lengthens shift times, and an ultra-low-viscosity fill has the most room on that measure. Signature Series ULV ATF pours at -62°C (-80°F) and measures 4,050 cP on the Brookfield test at -40°C, well under half the 9,755 cP the conventional Signature Series multi-vehicle grade records at the same temperature.

The published viscosity index is 134, against 165 for the conventional grade and 159 for the fuel-efficient grade. Those figures describe three fluids engineered around three different requirements, so the comparison is useful for understanding the lineup, not for substituting one grade for another.

Wear protection at 4.5 cSt

A thinner fluid raises a fair question about the film left between loaded parts. Signature Series ULV ATF returns a 0.39 mm wear scar in the four-ball wear test under ASTM D4172, run at 40 kg, 75°C, and 1,200 rpm for one hour, matching the scar the conventional Signature Series multi-vehicle grade records in the same test.

That result comes from the additive treatment rather than from thickness. The Signature Series formulation pairs high film strength with anti-wear and extreme-pressure additives, which is what holds protection in place when varying speeds and loads multiply torque across gears and bearings.

Heat resistance and drain planning

The formula carries the same heavy antioxidant load as the rest of the Signature Series line, which is what makes it resistant to thermal breakdown. Deposits are the specific risk being managed, since varnish and sludge restrict narrow oil passages and contribute to clutch glazing, and the transmissions that specify an ultra-low-viscosity fluid depend on those passages staying clear.

Drain planning follows the Signature Series pattern. Normal service follows the vehicle manufacturer's normal-service interval, severe service supports double the manufacturer's severe-service interval in passenger cars and light trucks, and outside the United States and Canada the manufacturer's recommended interval applies. Transmissions that call for a conventional grade instead take Signature Series Multi-Vehicle ATF.

Specifications Signature Series ULV ATF covers

This fluid covers transmissions and other applications that require any of the following:

• Ford MERCON ULV
• GM DEXRON ULV

Coverage as published in the AMSOIL data bulletin, checked July 2026. AMSOIL revises coverage when a formula changes, so confirm against AMSOIL's current data bulletin before ordering.

Service life

Normal service: follow the vehicle manufacturer's normal-service drain interval.

Severe service: double the vehicle manufacturer's severe-service drain interval in passenger cars and light trucks.

Outside the United States and Canada, change at the vehicle manufacturer's recommended drain interval.

Typical technical properties

Typical properties published by AMSOIL, checked July 2026. These are representative values rather than a specification, and they change when AMSOIL updates a formula.

Package sizes and product codes

Select a product code to open that package size on the AMSOIL product page.

Product documents

AMSOIL publishes the full technical detail for this product in these documents.

• Signature Series ULV ATF product data bulletin (PDF)
• Signature Series ULV ATF safety data sheet (PDF)

Where to order

Confirm this formula is the match for the vehicle or equipment in the AMSOIL product guides, then order Signature Series ULV ATF online. Existing members can sign in to apply the discount automatically.

Details and questions