I used the
Permatex Ultra Grey.
Quote:OEM specified. Designed specially for high-torque and high vibration applications, like those common in import engines, this premium RTV gasket maker exceeds manufacturers' performance requirements. Noncorrosive and low-odor. Maximum vibration resistance, with outstanding resistance to oils, cooling and shop fluids. Guaranteed not to leak. Temperature range -65ºF to 500ºF (-54°C to 260°C) intermittent.
When I was doing the head seal/plug on mine, I read up on the OEM recommendations in the listings at the Autozone and found the ultra grey listed by Suzuki and used it.