See How AMSOIL Performs in the Harley-Davidson® Milwaukee-Eight® Engine

AMSOIL Harley

Watch how AMSOIL performs in this 2019 Harley with a Milwaukee-Eight 107 engine after 1,000 miles of extreme-heat testing on the dyno.



See Why Loni Unser is into Going Fast

The Unser family has produced several notable racers over the years, including Bobby, Al Sr. and Al Jr. Loni Unser is aiming to add her name to that list.



Synthetic vs. Conventional Oil: The Definitive Guide

Synthetic vs. conventional oil

Many motorists are switching to synthetic motor oil for the first time. Find out everything you need to know about synthetic vs. conventional motor oil.



Do Older Engines Need Oil With ZDDP Additives?

Using a high-zinc oil with a high dose of ZDDP additives helps protect classic car and hot rod engines. AMSOIL Z-ROD Synthetic Oil contains 1400 ppm zinc.



The Difference Between Winter- and Summer-Blend Gas

Summer-blend and winter-blend gas

Summer-blend gas provides about 1.7 percent increased energy content, meaning it offers a slight boost in fuel economy. Here’s how else it’s different.



Break-In Oil: What is it and When Do I Use it?

Break in oil

Break-in oil seals the piston rings to the cylinder wall for maximum power and minimum oil consumption. Here’s how it works and when to use it.



Do I need a Diesel Coolant Additive?

Semi trucks lined up

Adding a diesel coolant additive, or supplemental coolant additive (SCA), midway through the service interval is easy to overlook and fraught with problems. Here’s a better way.



What Does Horsepower Mean?

Challenger burnout

One horsepower equals 33,000 ft·lbf/min (about 745 watts). We explain what it all means – and its connection to the London beer-making industry – here.