Just to provide one more data element:
1989 560SL, 150K
1 qt per 3000 miles or so
using 20W50 dino Valvoline, high-mileage engine formula

__________________
Craig Bethune

'97 SL500, 40th anniversary edition

'04 Olds Bravada (SWMBO's)
'06 Lexus ES330
'89 560SL (sold)


SL--Anything else is just a Mercedes.
(Kudos to whoever said it first)