New AMSOIL Z-ROD® 10W-40 Completes Line-up

Z-ROD® Keeps Classic Vehicles Street-Ready

AMSOIL Z-ROD® Synthetic Motor Oil protects engines on the highway and in the garage.

New 10W-40 viscosity joins the lineup, protecting engines on the street and during storage.

Taking your classic car or hot rod out of storage is an exciting time for enthusiasts. For many, it marks the end of a long winter or lengthy period of inactivity during which their prized car was stored under cover in the garage.

Storage invites engine-damaging corrosion

During that time, rust or corrosion may have formed on engine parts due to humidity and moisture from changes in ambient temperature.

Rust and corrosion can be just as devastating to an engine as dirt or sludge. It can flake off metal and populate the oil with wear-causing particles, which scour bearings, cam lobes and other parts before the filter has a chance to capture them.

AMSOIL fights corrosion

We formulated AMSOIL Z-ROD Synthetic Motor Oil to prevent this scenario.

It contains potent rust and corrosion inhibitors that protect the inside of your engine during storage so you can rest assured it will be ready to roll when you are.

Motor oil has no natural ability to resist rust or corrosion. Instead, special inhibitors must be added to the formulation to keep metal components protected. Not all motor oils contain sufficient rust and corrosion inhibitors to protect engines during long-term storage.

Added ZDDP for added wear protection

Flat-tappet cams, found in many classic cars and hot rods, present another challenge some motor oils aren’t formulated to handle.

Their design makes them especially vulnerable to wear. As the name indicates, the tappet, or lifter, is flat. During operation, the surface of the cam lobe slides rapidly over the surface of the tappet, producing high friction and temperatures. The camshaft and lifters are responsible for triggering the precisely tuned movements of the valvetrain. Here, the use of anti-wear additives becomes crucial.

Zinc dialkyldithiophosphate (ZDDP) is a commonly used motor oil additive that provides anti-wear protection and minimizes lubricant breakdown. ZDDP also exhibits mild extreme-pressure protection. As temperatures in the engine rise, ZDDP decomposes, and the resulting chemistry protects critical metal surfaces.

Because most V-8 engines of the muscle car era came standard with flat-tappet cams, the problem is prevalent to classic-car and hot rod owners.

Modern oils aren’t formulated to tackle this problem. They contain reduced ZDDP levels due to its propensity to harm catalytic converters. For that reason, it’s best to use a high-ZDDP oil formulated specifically for classic cars and hot rods, such as AMSOIL Z-ROD Synthetic Motor Oil. It’s available in 10W-30, 10W-40 and 20W-50.

AMSOIL Z-ROD Synthetic Motor Oil

• Added ZDDP to protect flat-tappet cams
• Long-term rust and corrosion protection

Solving the Challenges of Flat-Tappet Cams in Classic Car Engines

Summer belongs to classic cars and hot rods. It's the season when thousands visit car shows across North America and loyalists of every make and model cruise the streets to show off their rides. One of the big concerns among classic car owners in recent years, however, has been the abundance of flat-tappet camshaft failures that many attribute to the reduction of zinc and phosphorus in today's oil formulations.

Zinc dialkyldithiophosphate (ZDDP) is the most common zinc-based additive, and is used primarily as an anti-wear agent to prevent premature engine wear. It also provides corrosion and oxidation protection. However, because the zinc and phosphorus found in ZDDP can negatively affect catalytic converters, it has been phased out of motor oil formulations in recent years.
Reducing ZDDP content has drawbacks, as classic car owners have found. Older vehicles with flat tappet camshafts and, in particular, engines that include high-tension valve springs or other modifications that create high contact pressures can suffer premature wear due to reduced ZDDP levels.

Flat-Tappet vs. Roller Cams

The design of flat tappet cams makes them especially vulnerable to wear. As the name indicates, the tappet - or lifter - is flat. During operation, the surface of the cam lobe slides rapidly over the surface of the tappet, producing high friction and temperatures. A thin oil film is the only barrier that prevents the lifter and cam lobe from welding together. If the oil film fails or provides insufficient wear protection, the two components can eventually wear the flat tappet cam and affect valve operation. Engine power and efficiency can decline if the flat tappet cam cannot lift the valves enough to adequately charge the chamber for ignition or release exhaust fumes. Because most V8 engines of the muscle-car era came standard with flat tappet cams, the problem is especially prevalent to classic-car and hot-rod owners.
Roller cams, on the other hand, are differentiated by rolling contact rather than sliding contact. Although more costly, roller cams are common in most modern vehicles and can be retrofitted into classic-car and hot-rod engines.

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Demand for High-Zinc Oils

The abundance of flat tappet camshaft failures in classic-car and hot-rod circles has spurred the market for high zinc motor oils formulated especially to protect flat tappet cams AMSOIL Z-ROD® 20W-50 Synthetic Motor Oil (ZRT) and AMSOIL Z-ROD® 10W-30 Synthetic Motor Oil (ZRF) are specially engineered for these classic and high-performance vehicles. It features a high-zinc formulation to help prevent wear on flat tappet cams and other critical engine components. Because many of these vehicles sit idle much of the time, Z-ROD contains a proprietary blend of rust and corrosion inhibitors for added protection during longterm storage. Z-ROD Synthetic Motor Oil is designed to perform on the street and protect during storage.

Complete Vehicle Protection

Classic cars and hot rods need more than just premium engine protection. Many are modified to deliver increased power and torque, placing added stress on the transmission, differential and chassis. AMSOIL Synthetic Manual Transmission & Transaxle Gear Lube (MTG), Severe Gear® Synthetic Gear Lube (SVG, SVT, SVO & Dominator® Synthetic Racing Grease (GRG) offer advanced protection modified classic cars and hot rods need. These and other products are featured in the new Classic Cars Brochure (G3113).

Purchase AMSOIL products at up to 25% discounted as an AMSOIL Preferred Customer.