my question is about towing in 6th gear, sometimes called overdrive. My vehicle is a 6 speed auto transmission Holden Trailblazer with 3000Kg capacity, towing a 2000Kg ATM caravan. As you can imagine the vehicle tows easily and effortlessly and is quite happy to automatically slip into 6th gear or overdrive on long straight flat roads, of which there are plenty in Australia as you know. I have been told a few times now by well intentioned GNs that I should not tow in overdrive, something to do with gear ratios or lack of gear ratio in overdrive. I have never quite understood. One GN with a Holden Rodeo (older but similar vehicle) told me he gets better fuel economy when he does not allow his vehicle to slip into overdrive. Any thoughts or experiences please.
To really test this theory you would need to do some trip serial times over a few hundred kilometres with similar weather conditions.
Since I had a fault code come up on our car, 7 speed auto, the advice we got was from a unrepentant automatic engineer and a Nissan trained automatic specialist was to drive the car in sportsmode/manual mode where the torque converter is locked up to stop the slip in torque converter which heats up the oil.
Unbeknown to me as we were driving our car fairly quietly at relaxed speeds towing 2.7 tonne caravan but in fact I was hurting the automatic. We were out western NSW into South Australia wandering along when the fault appeared.
They both told me sports/manual mode, well I thought sports mode was when I wanted to drive the Ute like a sports car and manual when I wanted to hold it in gears. Now if the Nissan had called sports mode "hard work gear" thats where I would of drove it.
To say we get better fuel economy, maybe, only maybe. It did not change the fuel economy that much it was exciting noticeable.
I would advised you to seek out a Auotomatic Specialist then go to your friendly Holden Dealer to speak with their trained auto technician and ask the some questions about towing a couple of tonnes of caravan behind your car.
Question I would ask,
A. How should I use the automatic when towing.
B. What mode should I tow in. ie. D, Sports or manual.
C. How often should we service the transmission.
D. Will the transmission need a oil cooler.
I have now asked these question and to my horror possibly have shorten the life of my transmission by driving the car in "drive" most of the time. I did use sport mode in hilly country, manual going down steeper hills.
I have a 2014 Colorado Ute towing a 2.7t aluminium teepee. When towing, I start off in auto and when in 3rd change over to selective shift and look after things myself until going through towns etc and road works, I then let auto take over. I mainly use the tacho for revs and just check for speed now and then. I mostly am in 5th but when going down hills or long stretches of flat road slip into 6th without any problem at all. I notice my revs actually drop a tad and no sound of engine struggling.
At times I will just leave in auto and it mainly stays in 5th but as I do in selective shift, it sometimes slips into 6th for similar reasons to what I do above. Again, no engine struggling heard.
I must admit though, most times the Collie is in 5th and I am very happy for that to take place. Revs are just under 2000 rpm at that time.
Keep Safe on that road and out there.
__________________
Live Life On Your Terms
DOUGChief One Feather (Losing feathers with age)
TUG.......2014 Holden LT Colorado Twin Cab Ute with Canopy
DEN....... 2014 "Chief" Arrow CV (with some changes)
I think it's best to go by what your vehicle manual advises, as not all cars are built with equal capability. My current tug is very happy to tow in overdrive, but my previous one definitely wasn't. The recommendations by each of the manufacturers differed accordingly.
__________________
Cheers,
Tony
"Opinion is the medium between ignorance and knowledge" - Plato
I don't tow, but agree, no love lost running past a manufacturer's engineer. Be firm & push the bastards hard if required. If that fails.....
Write an old fashioned polite letter to the CEO (look up ABN info) to get answers if needed. I have done this a number of times to various companies & have never failed to get a competent person. Works a treat every time, use Times font in your letter!
What is the key torque range of the engine. Maybe you are a bit under the key RPM being in overdrive.
I've kept a lot of data on my car traveling. I do tend to get it into 6th, but getting up to 6th I need to get the car up to pretty much 100 then drop back to 95 for the long low stress runs. But have not noticed any real tangible difference in fuel efficiency from 5th to 6th on my car.
But as I said I am not towing & stick 98 in the car even though it can take 91, longer range is equal or a smidgen better than the price of 98.
The new all terrain tyres on my car use about 3% more fuel than the original road tyres.
__________________
Procrastination, mankind's greatest labour saving device!
50L custom fuel rack 6x20W 100/20mppt 4x26Ah gel 28L super insulated fridge TPMS 3 ARB compressors heatsink fan cooled 4L tank aftercooler Air/water OCD cleaning 4 stage car acoustic insulation.
Agree with others . step 1 consult the manual . step consult the dealer . step 3 consult an automatic transmission expert . step 4 DO NOT consult a grey nomad you will get 10 different answers from 6 different people ;)
A diesel engineer relative who also "does" auto's reckons that to prolong the life of the auto when towing you should use sport or manual mode where it exists and to keep the torque converter locked up as much as possible. An unlocked TC heats the oil which is not a good thing. With a manual if you're using top gear then as soon as you need more throttle to maintain speed drop down a gear.
Another relative ignored his advice and cooked an auto in less than 300km's by towing a box trailer with a large frontal area at freeway speeds in "econ" mode.
As he says, if you drive with a deal of mechanical sympathy you'll get good life out of everything.
-- Edited by markf on Sunday 19th of January 2020 10:38:00 AM
It depends entirely on the vehicle and what speed you are driving at.
Some vehicles do not like towing in top gear and will not lock the torque converter up. Others will. Also if you are towing at around 80kph you may not be getting fast enough for the converter to lock up.
Check your owners manual as they usually have a section on towing and whether or not they recommend towing in a lower gear or sports mode. It should make mention of whether you need an additional oil cooler or not as well.
Many of the current automatics are now very computer controlled, and will automatically select a lower gear if the conditions require it such as a rise in transmission temp.
If you have an automatic (which you do), you should always tow in sports mode. People who have trouble with their automatic transmissions and blame the manufacturer, usually find that the fault was their own as they towed in overdrive. Ask you service manager. If he knows his business he will tell you not to tow in overdrive, in your case, 6th gear.
Just read full chapter on towing in Amarok manual and no mention made of gear selection. Previously commented in another post that during January - February last year in extremely hot weather, found the rok ran more fuel efficient at 100kms in 8th (top gear). Selected manual mode for hills etc.
For what it's worth my Landcruiser manual states to tow in S5. ie. Sport 5th gear (6 speed auto)
My previous VW Touareg 8 speed had no mention and the dealer said to "put it in Drive and go"
Both cars use Aishin manufactured autos I believe.
__________________
"life is too short to spend it with people who suck the happiness out of you"
If you understand a little about engines etc . More so with turbo . Most are turbo diesels . Theres NOTHING wrong with turbo diesels as tow motors . Ideal imo ., what happens if towed in too high gear ? Is the engine AND turbo overheads as its working its guts out . Which creates very high temps . The strange part what some dont understand is changing down with higher rpm, lighter throttle is actually more efficient! The lower gears due to mechanical advantage is stronger !! For the same reason a 14 inch spanner is easier to undo a bolt compared to 6 inch . We often put higher aspect tyres on too which increases the vehicle final drive !
If you understand a little about engines etc . More so with turbo . Most are turbo diesels . Theres NOTHING wrong with turbo diesels as tow motors . Ideal imo ., what happens if towed in too high gear ? Is the engine AND turbo overheads as its working its guts out . Which creates very high temps . The strange part what some dont understand is changing down with higher rpm, lighter throttle is actually more efficient! The lower gears due to mechanical advantage is stronger !! For the same reason a 14 inch spanner is easier to undo a bolt compared to 6 inch . We often put higher aspect tyres on too which increases the vehicle final drive !
Yes. And quite a number of turbo diesel owners would probably almost die if you took their exhaust gas temp guage away from them...
I appreciate all comments. I failed to mention that I did consult my owners manual before posting the question and the manual is silent on the subject. I use the auto transmission manually on uphill twisty grades but generally let the auto do its job all other times. The times the auto slips into 6th/top gear while towing is only on dead flat roads, any incline and it kicks back to 5th. The only way to avoid those short bursts in 6th would be to always drive the box manually. Ill give it a go. Thanks to all.
I have a 2012 V6 Nissan Navara twin cab ute with 7 speed auto towing a 2.7 ton van. I always tow in sports/manual mode and only go as far as 5th gear. I am just under 2000rpm at 90kph. By using manual mode I also change back through the gears when pulling up at traffic lights etc or when going down hills rather than completely rely on the brakes. I have done 195000 klms without any problems.
__________________
Cheers
Col
(Picture of my beloved Molly (2003 - 2016) who loved the travels as much as I do. RIP old girl. Gone but never forgotten).
