Will this hurt my transmission?

[ninetynineSC2]

Will I damage the transmission if I coast to stop signs in neutral? I only want to do this to improve the fuel economy by lowering the rpm's to idle since (As far as I know) The S series cars don't shut off the injectors when you coast. I know some car's won't properly lubricate the transmission when they are moving in neutral and some cars do. I thought I had read that the S series transmission is being lubricated whenever the tires are moving, but I don't know how trustworthy that site was.

[wi111y]

I'm fairly certain that most EFI cars, saturns included, have the DFCO feature.

[jimboman]

I haven't read the specs myself, but I remember someone saying in another thread that the S-series have DFCO. Keep it in drive and you should be saving fuel.

[dbetz]

I used to do the same thing, but OldNuc and others here advised me to stop. Essentially, the constant shifting will wear out the trans and linkages faster. Not immediately fatal, but not recommended either.

The Saturns have the DFCO, which cuts fuel off to the injectors while coasting above a certain speed/rpm. So instead of using little fuel, you use *no* fuel. Below a certain speed (about 35mph for the Saturn) the injectors kick back in to prevent stalling. If you coast down and pay attention, you can actually feel the subtle change when the injectors kick back in.

Use it to your advantage coasting to stop lights/signs, on fwy off ramps, down hills to help boost your mpgs.

[PlasticCarsRock]

The gain in mileage would be very small, if any. At highway speed, there is DFCO (more related to engine speed than vehcile speed, although both will disable it when you're below whatever the limit is). On my gen1, DFCO stops once I slow below something like 1700rpm (45-50mph). If I manually downshift, the engine will stay off until you get pretty slow.

Even once DFCO stops, it's still burning very little fuel--the drivetrain is providing all the power it takes to turn the engine and accessories, so it needs just enough fuel to keep up with the air coming in (very little with the throttle and IAC mostly closed). I don't know for sure, but I expect it's less than idling in neutral (IAC opens to let in more air to power the engine and accessories).

In addition, you'll probably end up using your brakes more (without the engne braking to slow you down).

It won't really hurt the transmission, but it does mean more wear on the linkage.

I don't see any reason to do it...

[ninetynineSC2]

Ok, I'll just let her coast. Now that I think about it I sometimes feel a little kick when I hit the gas after I let it coast down hills on the highway, must be the injectors re-engaging.

[alordofchaos]

Pretty sure the Saturn transmissions stay lubricated. It was a big seling point that you could tow the Saturn with all 4 wheels on the ground behind an RV

I have a manual trans, so if I am coming up on stop and there is no traffic behind me, I will go into neutral and coast to it. No extra trans wear as I would have to take it out of gear once, and put it into gear once, either way.