thanks for all the comments, the 1994 mercury grand marquis 4.6 motor has 200,000 miles on it, it leaks a micro amount past the valve cover gaskets, no place else, the crank seals leak nothing. it doesn't foul the plugs, the platium plugs in it now have over 50,000 miles on them.
I have owned the car for about 7 years.
I drive 25 miles one way to work everyday, plus there is some short trip and longer interstate driving too,I average about 300 to 400 miles a week.
the oil burning is from ring blowby and maybe a little past the valve guides. it burns the most oil when it is getting close to being changed(dirty) and when I drive it harder (higher rpms).
in the past I have used 5w30 dino or syn blend for winter and 10w30 dino or blend for summer.
it seems to burn the same amount in summer that it does in winter, the oil gets dirty quicker in winter. I baby a cold engine too.
I have used tropartic and/or motorcraft oil in it the last 2 years, I tried penz dino one winter, a while back (yuck) never again (it didn't pump on cold mornings, with rod/main bearings hammering). of all the oils I have used in this old machine I like tropartic/MC the best
I was very much surprised at how much one quart of 15w40 reduced the oil burning, and figured maybe doing somwthing along the same lines would work in winter too.
from the above comments, it appears as if adding(mixing) one quart of 0w40 full syn isn't a good idea. I have never run full syn in the engine. and at about 6 dollars a quart I don't want run full syn in this old car.
I have never tried using 5w20 in it before, I would think on the interstate oil consumption would go up by doing it.
I also have never tried the high mileage oils.
oil consumption has not gotten worse in the last three years
[ September 16, 2006, 05:41 PM: Message edited by: MillerMan ]
