I bought my '03 last November in a private sale, which had 112000 km at the time. The previous owner seemed like an average joe, not one that'd be concerned about all the small maintenance items in a vehicle. I hate winter work, so although I was dubious that he was actually doing maintenance on a regular schedule, I put off most of the work in the summer. I did change the oil and popped in a new air filter off the bat, though.
I have heard conflicting reports about the K&N filters, some saying that they allow more particles in, shortening the lifespan of the engine.
I've stuck to simple things:
1. New spark plugs. They were at about 2/3rds of their lifetime, but I still changed them out. This was the biggest difference, I saw a 2MPG gain.
2. New differential oil and new tranny fluid and filter, which saw a very minimal increase, maybe 0.5MPG. I also flushed the coolant too, which I doubt did anything for mileage.
3. Inflating the tires a bit more didn't do much, and at the end of summer there was noticeable wear in the middle than the edges. So I deflated them back to 32psi.
4. Driving habits. I'm not an insane speeder, I go with the flow of the faster traffic, usually 20km/h (10mph) over the limit. I tried going just 10km/h over the limit, and while I saved maybe 1MPG, I've slowly gone back to my usual speeding habits.
5. Gas! In Canada, there are a few big chains (Mohawk, Husky) that advertise that they have a minimum percentage of ethanol in their gas, making it sound like it's a good thing. It's not, and with both my GM and Nissan vehicles, my fuel economy plummets with their gas.
I do want to try synthetic oil, but for some reason the owners manual for the '03 says "
NISSAN does not recommend synthetic type oils but recommends mineral based oils." The '04 manual also says this, but the '01 and '02 manuals actually recommend synthetic over dino oil.
Other more hard-core mods (I've done none of these) include:
- Lightening the load (using lighter rims, removing seats, removing A/C compressor, removing the spare tire (?), etc.)
- Improving aerodynamics (removing roof racks, air deflectors, etc.)
- Improving airflow. Either by making cold air more accessible (cutting holes in the body close to the cold air intake) or using a less restrictive filter (K&N's cold-air intake).
- Reducing drag. I've heard wonders about free/locking hubs, but that's mostly been with the generation of Pathy's before mine.
