1992 Mercury Grand Marquis burning significant oil
I have a 1992 Mercury Grand Marquis with the standard 4.6 liter. I bought the car with 62k on it over a year and a half ago. I have noticed since purchasing the car it burns about a quart of oil every 1000-1500 miles. I have seen posts and comments in regards to Ford engines, the 4.6 in particular burning oil at this rate is not uncommon, according to what I have seen. The car now has a little over 79k on it. Just got back from a road trip that took me from Denver to Carlsbad, New Mexico. Since doing the oil change 2 weeks ago in preparation for this trip the oil was full where it needed to be, the top end of the operating range ( I checked before I left). I noticed while on the trip and upon return the car appeared to be burning oil at a higher rate. The trip was a little over 1700 miles and I had to put in exactly two quarts of oil when I got back to get it back to where it was after the oil change. I have never had a car burn oil like this, at a rate of a quart every 850 miles seems ridiculous. I have an '88 jeep cherokee that I never put oil in between changes. Granted the entire trip I was going over 75 mph most of the way and we were driving in 100+ degree temps. I never notice smoke coming out of the exhaust even when I really hammer the engine, there are no other performance issues with the car, it runs really great. Is this normal, should I be replacing a main engine component? The car is absolutely not leaking anywhere! There is no oil on the under carriage of the car, I obsessively checked this.
I am not used to this at all, also does anyone know why the owner's manual would say to check the oil level when the car is warm? Any help is greatly appreciated!