Royal Purple 01512 Synchromax Manual Transmission Fluid 1qt

Royal Purple Synchromax is a full-synthetic, light-viscosity manual transmission fluid built for the gearboxes and transfer cases that call for an automatic transmission fluid or a thin gear oil rather than a heavy 75W-90. If your owners manual specs ATF or a light-viscosity lube for the manual box, this is the fluid that goes in it.

It is the right pour for a lot of the boxes people fight with: Getrag units that were filled with ATF from the factory, the Ford ZF5 and ZF6 five- and six-speeds, Honda and Acura manuals like the RSX Type-S that get cranky in third gear, Jeep Wrangler manual boxes, and transfer cases and two-cycle motorcycle gear boxes that specify a light lubricant. The Synerlec additive package is friction-compatible with brass and copper, so it protects the soft yellow metals in the synchronizers instead of eating them.

On the bench or under the truck, drain the old fluid and refill to spec, easiest with a hand pump run straight from the quart bottle. Expect the improvement to build over the first 50 to 100 miles as the additive plates the gears: cold shifts stop notching, second and third stop hanging up, and gear whine drops off. One quart is 32 fl oz; most manual boxes take two to three quarts and transfer cases one to two.