Lubegard 60902 Automatic Transmission Fluid Protectant, 10 oz

Why it's worth it

Lubegard's protectant tackles the things that wear a transmission out rather than the symptoms you can see. It lowers operating temperature, softens harsh shifts and quiets torque converter shudder, which makes it the one to add during a fluid change on a truck that tows.

Heat is what actually kills transmissions, and this targets it directly. Fluid oxidizes faster when it runs hot. Friction modifiers break down, seals age, and the whole thing spirals. Lubegard's LXE chemistry is built to bring operating temperature down, which protects everything else in the system. If you tow a trailer, sit in summer traffic, or run a vehicle past 150,000 miles, that's the most valuable thing on this list.

It's the shudder fix in this lineup. Torque converter shudder — that faint vibration at light throttle around 40 mph — is a fluid problem more often than a mechanical one. Lubegard specifically claims to eliminate clutch chatter and converter shudder, and owner reports back that up across GM, Toyota and Honda transmissions. Several describe pairing it with a drain-and-fill and getting most of the shudder gone.

From our review of 6 transmission fluid additives and stop leaks, by Genevieve Dubois, Home & Living Expert

What we like

• +Heat is what actually kills transmissions, and this targets it directly
• +It's the shudder fix in this lineup
• +Dealerships use it as a service add-on, which tells you it plays nice with factory fluid
• +It softens harsh shifts without making them lazy

What to know

• –It does nothing for an active leak
• –It's for automatics only
• –The benefit is hardest to see in easy driving