Hi Francois-
Normal consumption generally is in the realm of 0.25 -1.0 litre in 1000
miles (1600km)
An engine that uses more than a litre in perhaps 750 km is apt to have some
mechanical issues. Theres many ways oil can be consumed, leaked, or
incorrectly measured. Its OK to allow the car to burn oil down to the 'add'
mark on the dipstick before adding additional oil, as this will usually
give a more accurate idea of true consumption.
My personal view is most RR engines would benefit from a 5W-30 oil as a
measure to maintain overall cleanliness and minimal deposits in the
crankcases- synthetic oils such as Mobil 1 may also bear the investment.
Unleaded fuels are also a tremendous aid.
High oil consumption with no blowby is suggestive of too high an oil level
(perhaps wrong or poorly calibrated dipstick?) sticking oil control rings,
worn valve guides or leaks generally. Leaded fuel is prime suspect #1 for
ring sticking problems, in tandem with slow driving/short trips. Takes a
long time to warm up all that sump oil!
Odds are good theres nothing wrong, RR seems to be somewhat generous with
permitting oil consumption in thier Shadow engines which has good returns
for longevity generally. If the car does not make mechanical clatter, or
visible smoke, and runs well I shouldnt worry too much.
Occasionally, a car driven slowly around town normally will exhibit quite
drastic oil consumption within a few hundred km highway travel, due to
burning out accumulated moisture, fuel and other contaminanants in the sump
as the engine is operated continuously at a proper temperature. Once these
lighter constituents have been vapourized, and drawn out, oil consumption
returns to a normal level, but may reflect this process by being half a
litre to a litre below 'full'.
I'm sure others will jump in to make suggestions also;-)
Kind Regards
Brent Covey
Vancouver
|