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:?: Newbie here...

Any advantage to using synthetic oil in the Insight manual trans? I just changed the oil in the engine to synthetic, like I use in all my vehicles. On the subject of octane...this old gearhead seems to think that the little 900cc mill might benefit from premium with that high compression ratio. But, then again, I suffer from 'old tech' thinkin'.

Thanx !
 

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I'd keep using Honda transmission fluid in the Insight. The replacement interval is low enough and there's no telling what it will do to the efficiency. Synthetic might protect the syncro's a little better but it might also hurt mpg's. I was contemplating switching to some Redline MTL but decided to stick with the Honda stuff. As for fuel, I'm pretty sure people have tested high octane fuel and found it doesn't help mileage. This might be from the fact that the Insight not only has high compression ratio's but it also runs very lean so it needs a lot of compression to ignite so little fuel.
 

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Remember that Honda MT's use _engine_ grade oils in the 10w-30,40 range.

If you drive in the _hyper_ MPG style then _theoretically_ synthetic MTF (10w-30 engine oil) should help some small percentage.

But in some situations its too slippery and the synchros won't grab correctly causing gear rake (you'd feel it when shifting). The only solution in that case is to switch back to Honda's special MTF blend (or probably a good quality 10w-30,40 motor oil).

I use in in all my Hondas and have for many years without problems. But as in all thing automotive YMMV. (total aggrigate miles in 4 Hondas of 500K+)

The "best" grade for an Insight has been "debated" to death in here (I hope ;) ) try the forum search feature :!: There are several threads on both your questions :!:

HTH! :)
 

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kapps said:
Synthetic might protect the syncro's a little better but it might also hurt mpg's.
Synthetic oil will not hurt your gas mileage, as it can only help it. Unlike using premium gas in an engine that is designed to run on regular. Premium sythetic oil is something all together different.
 

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I never noticed any difference in performance or mpg between 87 and 93 octane. And I thought the Insight uses a 1 liter engine, not 900cc?
 

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Resist said:
kapps said:
Synthetic might protect the syncro's a little better but it might also hurt mpg's.
Synthetic oil will not hurt your gas mileage, as it can only help it. Unlike using premium gas in an engine that is designed to run on regular. Premium sythetic oil is something all together different.
We're not talking about engine oil. Synthetic engine oil of the same 0w-20 viscocity will be better for the car and help mileage. In the gearbox, you'd have to find out exactly what the specs are on the Honda fluid and try to match it.
 

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Just need to add a few points.

*If you are still under the powertrain warranty, the use of anything but Honda MTF could void your warranty.

*Most cars use "Gear Oil" in thier manual transmissions. It is usually 75 to 90 weight. You see it on the store shelf saying it's for manual transmissions. You should never use "Gear Oil" (Sythenic or otherwise) in a honda manual transmission. It is not specificed, it is the wrong oil.
 

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kapps said:
We're not talking about engine oil. Synthetic engine oil of the same 0w-20 viscocity will be better for the car and help mileage. In the gearbox, you'd have to find out exactly what the specs are on the Honda fluid and try to match it.
I already understood we were talking about the trans oil. My response is the same. If the transmission gears flow better, the end result can be better fuel mileage.
 

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I agree that in theory lower viscosity, better oil could improve mileage, but the effect would be tiny compared the the effect in the engine, because the friction in the transmission is very small compared to the engine, regardless of what oil. So I'd be more concerned about using the right thing for longevity and warranty than improving mileage.

You can tell how little it matters: Coast down a hill in neutral. Shift into second, while keeping the clutch depressed. You'll feel little or no increase in drag. Now lift the clutch, and you'll feel a big drag.

Charlie
 
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