Any testing on mpg effects of using various gear oils?

[suspectnumber961]

* regular dino gear oil

* full synthetic (same viscosity)

* synth ATF with added Lubegard or Militec or moly additive

[luvit]

i saw a 3mpg increase at 72mph on my first tank. (over 11% increase)..
with the blizzard, i can reliably get another reading this week.
maybe next week or so.
full synthetic engine oil and full syth trans fluid, same velocity for my accord

[Lazarus]

You can start here. Some good stuff in there.

[Christ]

In theory, you shouldn't see a gain from using synth over conventional in the same viscosity.

[luvit]

i should double check the oil that was put in my engine.. the oil change place looked-up my car to choose the syth oil

[suspectnumber961]

Originally Posted by Christ

In theory, you shouldn't see a gain from using synth over conventional in the same viscosity.

As far as I know...viscosity is more controlled with synth vs dino gear oil...meaning that when cold synth is thinner. One person claimed that after changing to synth gear oil...same weight...he could coast further with synth oil.

I had an '86 Escort that used ATF in a manual transaxle....thinking that using synth ATF with a good additive might work...but might be risky too.

[suspectnumber961]

Originally Posted by Lazarus

You can start here. Some good stuff in there.

Good link!

[Christ]

Originally Posted by suspectnumber961

As far as I know...viscosity is more controlled with synth vs dino gear oil...meaning that when cold synth is thinner. One person claimed that after changing to synth gear oil...same weight...he could coast further with synth oil.

I had an '86 Escort that used ATF in a manual transaxle....thinking that using synth ATF with a good additive might work...but might be risky too.

Ford recommends the use of Mercon-based fluid in almost all their manual transmissions, with few exceptions, that I'm aware of. You're correct thinking that synthetic, as a rule, is more stable. I'm not sure this applies in a transmission as much as in an engine, but I can't really support that thought.

Using synth ATF that applies to the same specs as your original trans fluid will be fine on it's own. You can go to Ford dealer and get a 4oz can of friction modifier, but it's probably not necessary for the older trans?

[MetroMPG]

If you search bwilson4web's posts, you will also find documented testing showing the effect of changing gear oil type/viscosity in his gen. 1 Prius.

[MetroMPG]

Originally Posted by Christ

In theory, you shouldn't see a gain from using synth over conventional in the same viscosity.

The viscosity stability of synthetic gear oils should return better efficiency in cold conditions. It's an issue for transmissions/differentials, since they don't benefit as much from the heat of combustion as engine oil does.

I can find dozens of links that claim to support this notion.... but can I find one on short notice that appears to have some science behind it? Nope!

Anyone?