10W-30 SEMI SYNTHETHIC CAT COMPATIB

The Sierra 18-9421CAT-3 is a 10W-30 synthetic blend outboard engine oil. It meets the requirements of modern 4-stroke recreational engines, with or without emission catalyst systems. This oil is approved for all 4-stroke applications including Outboard, Sterndrive, and Inboard engines.

This oil exceeds all 4-stroke requirements, including FC-W and FC-W Cat Compatible standards. It provides superior corrosion protection under extreme conditions and offers industry-leading wear protection and deposit control. The formulation capitalizes on ZDDP anti-wear additive technology, preventing phosphorous depletion and extending emission catalyst life. It is NMMA FC-W Certified and specifically recommended for use in Mercury 4-Cycle Outboard Engines requiring 10W-30.