what kind/weight of oil to use?

2000 cougar. 2.5L?? I'm planning on just using the same oil I usually use ...Castrol GTX. Book says to use 5w30 but would 10w30 be ok?? Also I usually use AC Delco filters in my chevys, but what about the mercury? any recommendations?

10w30 will work... really you can put whatever weight oil you want in, 5w30 is just what the manufacturer recomends because that is what works best under normal driving conditions. the type of air filter you want to use is a motocraft filter, motocraft is used for all ford,linclon,mercury vehicles

thanks for the reply! I used 10w30 and a motocraft...which I guess is the equivalent to the AC delco/chevy.

There's some good discussions on engine oil weights and what to use on the net, google it.

But as for your car, my opinion is that 5W-30, 0W-30, 10W-30, and the similar W-20's are all good. The W-20's give you very slightly better performance and gas mileage, the W-30's last a little longer, and the 0-10 is your temp range, 0 for colder weather -30 degrees to about 80 degrees (range just from what I remember, not accurate) 5 for normal, and 10 for really warm temps (never freezing weather).

Try to avoid mixing oil brands and avoid aftermarket oil additives (some can break down the detergents in the oil already) and use synthetic for less oil changes and better oil when you get to the change.

Everyone is looking to get the best gas milage possible so I would use the recommended 5W-30 instead of the 10W-30. I use synthetic in all my vehicles and change it at 5K miles. Yeah, I know they say you can go longer then that between oil changes but that's my preference. When I used to use GTX it was every 3K miles.

The 5/10 doesn't have any major effect on gas mileage, it's the viscosity and really only effects the temp. range that the oil does it's job. However, you are right that the lower viscosity will be better as it will reduce oil pressure through-out the engine.

It's the W30 or W20 that effects gas mileage but it's only about 1 MPG or less and the weight really effects the durability of the oil. That's why I use 5W30 in my cars but if you live in warmer climates where it rarely gets below freezing then a 10W oil would be better.