This is Turtle.
I have a 1990 LS-400 and it has 193K miles on it and runs good. Now my R.P.M. gauge went out on me about 3 months ago but Have not looked into fixing it yet. I've used Castrol 10-W-30 in it for the first 150K then went to 20-W-40 there on. It uses no oil between the 3K miles of the oil change, grease job, and filter change [ Wix Brand ] . I expect 400K miles out of it.
TURTLE