Is using 5th gear at 40mph messes up my engine?

[IllusionX]

i only get high 30's. my last tank was somewhere at 38MPG.

i'm sure it's the Quebec roads... and Montreal traffic.

[DerFlosser]

Originally Posted by Yaris Hilton

There's no "threat" to "lugging the engine." Won't harm it, as long as you're not causing heavy detonation. Accelerating at ~70-80% load at RPMs peaking in the 1500-2000 RPM range before upshifting is a popular approach to improving fuel economy with a manual transmission in Yaris-class cars.

Agreed...I was speaking in theory. That was the general concern indicated by the post topic, otherwise one could drive 20mph in 4 gear if it were economical to do so. Lugging the engine is not good for the car period and even light detonation is not healthy. The car is designed to withstand some surely, but continued light detonation will ruin your motor unmistakably.

[tomato]

The guys who know what they're talking about have already spoken, but I'll add my 2 c anyway, I think your friend is wrong. It was true of other cars like my old Honda (you could be in 3rd gear at 45 and the engine was still plenty confortable) but I don't think its true of the Yaris. On the Yaris, you have to shift gears much sooner and I found myself in 4th and 5th gear at relatively low speed, no problem, and that is the way the Yaris wants to be driven, I think.

Ultimately, I go by the sound of the engine. After a while, you get used to your car and you know exactly when to shift, even without a tach.

Hope that helps.

[eTiMaGo]

yeah it's nonsense... I usually cruise along on normal surface roads at 50-60km/h in 5th gear easily... of course if you need to gain some speed you'll have to shift down...

[SilverBack]

Entering 5th @ 40 MPH is my usual shift point. Never had any problems

[deerebilt]

I usually shift at 1400 to 1500 rpm and run 45 to 50 mph on a rural paved road every day. Have 21k mi on my 08 Sedan S w/no problems and get 50 to 52 mpg. I have a Scanguage II and adjust cruise to best mileage speed. My overall avg mpg since brand new is 43.4. I am really impressed with the Yaris

[john21031]

In my opinion, the risks of causing harm to the engine while driving in a high gear at low speed is significant. Imagine riding a multi speed bike in the lowest gear uphil. This is the time when sproket and chains fail the most, due to highest load, on small number of teeth.

The power needed to turn the smaller diameter of a high gear is much greater than needed to turn (rotate) the lower gear. This stresses the engine, specifically it creates high forces on the crank shaft bearings, wearing them out prematurely.

Another problem of loading the engine at low rpm is a possibility of inadequate oil delivery due to lower oil pressure at low rpm.

Driving these new cars and not seeing major engine problems is not an indication that the engine is not wearing out prematurely.

[nerp]

Originally Posted by john21031

In my opinion, the risks of causing harm to the engine while driving in a high gear at low speed is significant. Imagine riding a multi speed bike in the lowest gear uphil. This is the time when sproket and chains fail the most, due to highest load, on small number of teeth.

The power needed to turn the smaller diameter of a high gear is much greater than needed to turn (rotate) the lower gear. This stresses the engine, specifically it creates high forces on the crank shaft bearings, wearing them out prematurely.

Another problem of loading the engine at low rpm is a possibility of inadequate oil delivery due to lower oil pressure at low rpm.

Driving these new cars and not seeing major engine problems is not an indication that the engine is not wearing out prematurely.

Understood. That's why we're all saying that 40-45mph in fifth is perfectly fine on flat pavement. We like to downshift when going uphill or needing to accellerate.

[gaffo]

Originally Posted by Syroyizhka

I was driving with my friend the other day, and he yelled at me for using the fifth gear when i was going like 44 mph, I usually use it after 40 mph if driving on an even payment, however if its slightly up the hill I use 4th or even 3rd.

WTF!!!!!!!!!!!!!!!!!!????? 5th at 40??????

at 40 I shift FROM 2nd to 3rd!!!

Originally Posted by Syroyizhka

He claims that he only uses the 5th on his Scion after 60 mph.

He's right - as the Yaris has even taller gearing, that makes it shift to 5th at 65 mph.

Which is what I do. Under 65 to 50 mph I'm in 4th.

Originally Posted by Syroyizhka

Should i listen to him?

yes.

Originally Posted by Syroyizhka

cuz i think the manual said after 45 mph it was alright to use 5th. what are the most fuel efficcient speeds to change the gears, considering you're driving on a even payment?

mechanically you should be fine runing in 5th at 45 mph - as long as that is above "lugging" speed, which i think it is. and you will get a little better gas mileage, BUT you will pay for it in POWER.

I like to drive within the POWER BAND of my car: I probably lose around 3-mpg (I average 37 mpg, and you probably get around 40 mpg). More power give me more control on the road - power to maneuver out of harm's way when that 18 wheeler decides to move into my lane without signaling/etc..

1st 0-18 mph
2nd 19-38 mph
3rd 39-50 mph
4th 51-65 mph
5th 66-90 mph


not been over 90 yet.

[gaffo]

Originally Posted by Kal-El

Sorry, but your friend knows nothing about cars. Being in 4th at 44 mph is actually starting to rev your engine higher than it should while cruising on flat ground. Keeping it in 4th until 60 (in a 4 cylinder car) is now racing your engine and should only be done if you need hard acceleration or actually going almost 60 uphill. So, if your just cruising on flat ground, you should shift into 5th after 40 mph for optimal mileage and the least amount of engine wear.

nonsense. 4 bangers run at higher rpms than v8's and we have synthetic oil now.

[gaffo]

Originally Posted by tomato

The guys who know what they're talking about have already spoken, but I'll add my 2 c anyway, I think your friend is wrong. It was true of other cars like my old Honda (you could be in 3rd gear at 45 and the engine was still plenty confortable) but I don't think its true of the Yaris. On the Yaris, you have to shift gears much sooner and I found myself in 4th and 5th gear at relatively low speed, no problem, and that is the way the Yaris wants to be driven, I think.

Ultimately, I go by the sound of the engine. After a while, you get used to your car and you know exactly when to shift, even without a tach.

Hope that helps.

with respect, you are incorrect in regard to the gearing of the Yaris. It has a very tall gearing. much more so tham most manual cars.

for example my old TR7 would cruise at 65 mpg in 5th with 3600 rpm. i'm pretty sure the Yaris in 5th at 65 will give a lower rpm (though thanks to Toyota' incompetence in not offering a tach on the american cars we will have to contact a European to verify).

[SailDesign]

The yaris at 65 in 5th is turning about 2800 rpm. PLENTY of power available at that speed for passing if you want. IMHO, using the engine the way you quoted, gaffo, is fine for "getting up there", but if you're just cruising you can happily slip it into 5th at 40-45 and lollop along. My '07 was blissfully happy that way going to work in the morning.
OTOH, if I'm playing, 2nd takes you to 60, 3rd to 85-plus, and the rest is gravy. But that's the lead foot talking.

[Dorkinheimer]

I usually put it in 5th at 45 MPH, and would put it in 6th if there was one at 70 MPH ;)