Downshifting in 6th and 5th, when ?
 

My question is, when driving with "light throttle" for long distances on flat roads in 6th gear, up till what lowest (safe) rpm can be cruised without any danger for damage of engine/eccentric shaft etc.
Of course the accelerator pedal should be cautiously touched in that situation.
My very personal feeling is that approx. 3000 rpm is lowest in 6th gear, then shifting down...
Or could approx. 2500 rpm still be acceptable before the necessity of shifting down from 6th in 5th.....or could it even be lower...?
What lowest rpm before downshifting from 5th to 4th gear...?
Of course my daily driving varies up to 5000-6000 and sometimes >7000 rpm/redlining to keep my valves free..
Any view/message is highly appreciated...!!!

(Via the search function I could not find a proper link or thread; if somebody knows a relevant one, please inform.)

when you feel the car is slowing down even when you press down the gas pedal its when you downshift.
could be at any rpm.
same goes for upshift. when you rpm start to climb slowly at given gas pedal position, time to upshift.

That's roughly how I do it. I only use 6th when I'm cruising on the highway, or somewhere at about 55+. 40-50, I stay in 5th, unless I'm going uphill and it's requiring a bit more than a little throttle, then I downshift. Same with 4th even.

I try to keep the load light on the engine when I'm just casually driving, and the rpm's are lower.

@jasonrxeight
@MS Addict

Thanks for both replies!
Best regards, Ruud

Rudolph, can you tell me why when cruising in top gear, should the gas pedal be cautiously touched ? If its cruising at 3000rpm, even slamming the pedal to the floor isnt going to do much.

In 6th at 3000pm I would indeed run with "light throttle" and would never slam it; probably only pressing the throttle very very soft and with short stroke if some light acceleration is needed, or better I would shift back; for firm acceleration I would shift back in any case....

Why would you do that, do you really think the power output at 3000RPM will hurt anything? This engine makes NO power down that low as well as even less torque.

Another thing is that since it's drive by wire, the throttle body position in 6th gear at 3kRRPM is pretty much the same whether you have the gas depressed 40% or 100%.

Rudolph, I would suggest some kind of driving course.

The way he is talking about driving will do no harm to the engine or the car. Just because that is his style of driving does not mean that there is anything wrong with it. While it is no where near as aggressive as most on here probably drive there is no reason to hate just because he babies his car.

I think you would burn more gas at low rpm in 6th gear than driving at a bit higher rpm's in 5th. I know I do in my 8/

Chad D I read on here that around 4k-5k rpm is the best gas mileage. I do not understand how or why they may even be wrong, but this is just what someone said(I think it was MazdaManiac). On a long trip I have never tried using 5th rather than 6th but I will try next time, in 6th I normally get 22/23 mpg @ 75-85.

/\ that seems about right. I never use 6th when I am driving 100km/60mph or slower.

I try to avoid "lugging" whenever possible, excessively loading the engine.
Especially with this car, when in doubt, I downshift.

Stressing the engine with high RPMs probably isn't as much an issue today as it was in the past.

I did a very unscientific set of tests on my 07 6 speed. I drove the same route (mostly taking the kids to/from school ~30 km semi-rural round trip twice a day). I drove as smoothly and gentle on the acceleration as I could (within normal traffic).

I did a couple of tanks of gas religiously shifting between 4K and 5K rpm. I then repeated with a couple of tanks of gas religiously shifting between 3K and 4K RPM.

I got (on average) ~290km low fuel light out of a fully topped up tank of gas for the 4K-5K RPM weeks.

I got (on average) ~300km low fuel light out of a fully topped up tank of gas for the 3K-4K RPM weeks.

As much as was possible, I kept the variables the same. Same route, same time of day, etc. etc. My conclusion was that 3-4K got better mileage, but not enough so to dramatically alter my driving patterns. So I drive between 3-5K when just cruising around. :)

I don't have anything to say regarding the topic, just wanted to say very nice sig pic Jason. The paint looks immaculate.

The problem is even if you tried to keep everything the exact same it was not, a 10km per tank difference is so tiny that it could be affected by a lot of things. Its very hard to get an accurate test between multiple tanks if not impossible unless you are on a road trip maybe.

I don't really worry to much about my gas mileage, I just know its bad. I get 16 mpg in the city but I usually try and shift either above 6k or below 3.5k so my car is not as loud(3.5k to 4.5k midpipe buzz sound, 6k puts me over that when I shift).

My shifting is simple. When cold upshift at 3.5/4.5 k rpm. When warm I cruise at around 5 k (depending on speed limits, usually 5 MPH over) in third gear through town. On interstate I stay mostly in 5th unless I feel like doing 80+ then I'll grab 6th. I downshift when cold usually around 2/2.5 k and when warm at 3.5/4 k. I pretty much try to keep myself in a 4.5/6 k range so throttle response and power delivery is good.

In most (not all) driving situations, this is not true - according to my scangauge readout. This is especially true in the manual transmissions, where the relatively low gearing is already letting the engine turn high enough RPMs at highway speeds.

For steady-state cruising, that's just a waste of engine wear and fuel...

wow compared to everyone i drive a lot less aggressive when cruising.

i usually shift to 6 @ around 45 mph or 3k rpms from 5th gear.

when i'm driving at around 70-75 im crusing @ about 4-4.5k RPMS

i never stay in a gear crusing at around 4k RPMS, unless i need to.

I tend to enjoy cruising @ around 3k rpms when im driving lightly for better mileage

Section 5-10 - "Recommendations for Shifting" outlines shift points.

Downshifting near idle rpms should not cause any harm to the engine. I personally will tend to let the engine speeds drop no lower than 2k while in motion prior to downshifting.

@maskedferret
Thanks for the tip, indeed I found the up- and downshifting tables etc. in the English language on the internet...
Very strange, in my owners manual in the Dutch language they are lacking completely...

for normal driving, try to keep the rpm above 3k.

This is an interesting thread on lugging an engine.
Contrary to popular belief, you can lug an engine at high RPMs.
The definition of lugging is in the thread.

The issue with low RPM high load appears to be oiling related and in recip engines, stress on conrods and bearings.

To visualize what lugging may do to a rotary motor, imagine a rotor being turned slowly with high force exerted on the apex seal against the housing, the apex seals effectively scraping oil from the inner housing wall potentially breaking through the oil film. Also IINM, lower RPM means less oil via OMP?

On the contrary, a rotor with low load and high RPM has centrifugal forces to deal with, but the higher speed creates something akin to a hydroplaning effect where the apex seals skim over the oil?

I've understood that materials can withstand substantially more force for instantaneous moments in time before yielding, but a sustained force will have it yield with significantly less force. This seems to hold here also.

Can't find a definitive answer though.

http://www.bobistheoilguy.com/forums...Number=1143775

I'm in 4th gear in just about every situation in the city once I get up to 45 mph. I at least want to be able to give it some gas and get a response while driving just in case I need to for whatever reason. In 6th @ 45 seems like it would be pretty sluggish but I haven't tried it.