Mercury - 25W-40 4-Stroke Oil Change Kit L6 Verado Series Marine-Grade Components 8M0188359. Overview. There's something deeply satisfying about giving your outboard the kind of care that keeps it running strong season after season. When you're cruising offshore or sliding into a quiet cove, you want the comfort of knowing your engine is protected from the inside out. An oil change may not be the flashiest part of boating, but it's one of those simple routines that keeps everything smooth, stead