So my car has a few new things changed:

Motor oil (Valvoline 50SAE) 200 miles ago
Factory spark plugs changed 3,500 miles ago
Factory spark plug wires changed 800 miles ago

Occasional use of MMO

Driving habits, not too hard, usually don't boost 2nd turbo very often. Rarely WOT. During these cold days I usually let the car warm up a good 6-8min and don't drive past 2,500 rpms until after a few miles. Usual cool down time ranges from 4-6min.

Full tank of gas: Just over 200 miles.


Now I think that's pretty bad for my carefulness. I'm thinking it could be because of all the time that I leave the car in idle like warm ups and cool downs..... ??

Any help is good help.

-Dan

 

How bad are we talking? what kind of gas do you use? How many miles on your engine?

 

Oh, and has the bad mileage been a sudden thing or has it been this way all along?

 

That's about average. Check the other "gas mileage" threads:

https://www.rx7club.com/forum/showth...ht=gas+mileage

https://www.rx7club.com/forum/showth...ht=gas+mileage

 

BTW, that's a little excessive.

Just start the car up. Allow the rpms to settle and then drive the car without getting on it until it warms up. It's not really a good thing to just let the car sit there to warm up.

For cool down, just stay off boost for the last few minutes before you get home... let it idle for a minute and then turn it off. If you car isn't moving, you aren't cooling it all that much, just promoting heat soak.

 

I think it's a combination of all of your excessive idling. Do you make a lot of short trips? I get about 150 to 180 miles per tank around town, but around 350 to 400 per tank on the highway.

 

I've noticed the same thing lately. I think it's the cold weather and all my idle time. My car takes about 10-12 minutes to warm up completely ... then about 3 miles of drive time before it's ready for some boost.

Before I would get between 250-300 around town ... now i'm lucky to get 200. Since it's starting to warm up again ... I'll just deal with it until i can do some decent testing.

 

straight 50 weight oil is WAY too heavy for a rotary you should be running 10w-30 in even the HOTTEST climates (per MAZDA FSM).
and using heavier oil will reduce your gas milage.

 

Change your o2 sensor if you haven't already. You'll notice better performance and higher gas mileage.

 

I was going to write essentially the same thing. Start it, get comfortable, put your seat belt on, and go. Just take it easy until it's warm. Sitting at idle to cool down is generally a bad idea. You should have done your cool down the last few minutes before you arrived at your destination. Any time you are sitting at idle, there is no air flowing thru the front of the car, so your coolant isn't getting any cooler.

I do most of my driving around town, and get around 12 MPG. On the highway I think its about double that. Also, I don't think anyone uses that kind of oil. I use Mobil1 15/50. I recommend it.

Adam

 

I use 15W-50 synthetic oil in my engine, works great. A lot of people use 15/20W-50 in their engines.

 

synthetic is a no no

 

Uh, that's not exactly true. You should do a search for "synthetic" on this forum. Here's one thread:

https://www.rx7club.com/forum/showth...threadid=23430

 

Okay, I'm a little confused . I thought the point of cool down was to let the turbos slow down while still being lubricated? If this is true then if you're not on boost for the last few minutes of driving, then why would you sit and let the car idle before turning it off?...Not sure if it sounds like I'm attacking, but I'm not...I'm asking a serious question. Because if I'm not on boost for the last few minutes of driving, I just turn the car off as soon as I park.

 

little off topic, but what kind of gas mileage does the 3 rotor cosmo get? it must get like 8 miles to the gallon in the city.

 

Maybe a minute is a little exaggerated, but I usually just don't kill the car as soon as I hit the parking spot. I don't have have any technical reasons why, just feels better.

Usually I'm putting away CD's or getting stuff together to take out of the car so it's not a big deal.

 

The turbos slow down as soon as you let off the gas. They do not need a "slow down" period. They do need a cool down period if you have been boosting the car.

Pineapple Racing reccommends synthetic oil, as do many other rotary engine specialists.

 

To answer some of the questions directed at me:

*I'm on the 2nd motor and about 47k miles on it.
*I only use premium 91 octane from either Chevron or 76



I'll try to cut down on the warm up and cool down time but it's just sort of a habit of making sure my car is carefully warmed up and shut down.


BTW, how much is a new o2 sensor?

As for the oil...... I think I'll stick with dino oil rather than synthetic.

Thanks for the replies guys.

-Dan