The OEM Toyota oil pan gasket for the 3FE is a 1 piece cork gasket 12151-61011. It is glued together at the factory. The rear arch is notorious for leaks simply because it is difficult to clean properly before installation of a new gasket. The sealing surface of the front and rear arch are the...
And I respectfully suggest you read up on viscosity. A 30 weight is a 30 weight regardless of the first number in a multi-grade motor oil. 5W30 will have the same lubrication qualities of a 10w30. It just flows better at lower temps.
But hey, I guess my old 91 with over 300K on the old 3FE is...