Originally Posted By: andrewg
I've got an '04 Mercury Grand Marquis....great car! I used to have a 1999 Crown Vic...also a great car. Yes, the 5w-20 will work well and be of no concern. I think you have a six quart sump but just look in the owners manual and NEVER soley depend on just opinions for something that important. How many miles do you have on the car? Did you pay book for it, or less?
Make sure you go through all the fluids since it's a used vehicle. I had the tranny serviced, the brake fluid changed, differential fluid changed, oil/filter (an added AutoRX), fuel filter changed, coolant changed, and added a bottle of Chevron techron for the injectors. The thing runs like a TOP! I'm anal about things....that's why I had all the service done on it. I just get worried about used vehicles until I fully have everything done. I'm sure I went overboard though. These cars are tough as nails.
Thanks guys for all the answers. I guess my stash of 5w-30 will remian in stock for the foreseeable future and I'll be shopping for deals on 5w-20.
The car is a one owner car, 39,600 miles I paid $6700 out the door. It's in mint shape, no rust, no scratches, no dings, no rattles! Micheling tires with a bit of life left too. Rides very smooth. Nice highway cruiser. This upcoming weekend I'm taking a little trip out of state, and I'm eager to see how she runs on the open road. I've read lots of owner reports about getting up to 26 mpg. Pretty impressive for a big car. I hope I'm that lucky, but being winter, I'd be more than happy with the 23 mpg rating it came with.