Towing in Overdrive – ON or OFF ?

I’ve noticed a lot of people on social media ask whether it’s better to keep in overdrive when towing or drop back a gear.  I drive an automatic and drive to conditions.
 I usually keep overdrive on when on the flat however I drop back on hills and turns and always when going down hill, letting the gears slow me down.

I raised this subject with Chris Blakemore … here’s his reply.

This topic gets raised often, and it’s kind of one of those Nissan/Toyota topics.

For some people there will only ever be one answer.

If you ask the boys at large dealerships in Alice Springs and other repairers in similar areas, they won’t hesitate in suggesting owners drive in top gear. It brings in bucket loads of work for them.

For me, I suggest to use what is appropriate to the conditions and load.

For an example, a little while back we took a fully decked out  3.0L Auto Patrol with a Kimberley Kamper hooked up into the Flinders Ranges. Now as you can imagine that was one heavy set up. I also had the luxury of watching the EGT’s (Exhaust Gas Temps) to monitor engine operation. That machine is well set up and can happily tow that camper in top gear all day. However this particular day was rather hot and EGT’s started to rise so I dropped down a gear and temps went straight down. Why, because it reduced the effective workload on the engine. Same happens with gearboxes and especially autos. I run engine temp and auto box temp monitoring on my own Landcruiser, and it tells me exactly what I need to know. When working the vehicle hard when towing, which I have done with a camper and also a car trailer at times, the auto box temps rise quite high. I drop a gear from overdrive back to the 1:1 ratio and take that workload off, as well as backing off a little, then the temps also drop dramatically. I can see this happening with my digital read-out of real temps on the go.
Unfortunately people forget that when towing a big van they are using the vehicle at its upper limits, and that’s not always ideal.


Consider suspension.

When people load up the vehicles with accessories and slide on campers and other goodies, they are working the standard suspension to the limit and usually soon understand it requires replacement of the suspension with upgraded components.
Yet when towing a huge weight at the vehicle’s driveline upper limit they expect the standard trans to still do its job without arguing. Its not going to happen, especially in these ‘built to an engineering cost-driven minimum’ modern vehicles.
 People need to buy a vehicle appropriate for the intended use, service them regularly, and use the vehicle gearing and engine in consideration of the workload. 

It’s called Mechanical Sympathy.

In the absence of upgrades to a vehicle trans, take the work load down a notch and drive in a lower gear. 
An auto trans rebuild in a 200 series Landcruiser will probably put an easy $7K dent in your bank balance, if not more. That’s a lot of fuel.

While we’re on fuel … careful driving in a lower gear can actually keep fuel use down. 
Often it takes more throttle input, especially on rises to maintain say 90kph in overdrive on a slight rise than if in a lower gear.
 When the 200 series Landcruiser hit the market with their 6 speed auto, many people complained about the constant changing from 6th to 5th on every rise.
 Its not that the big V8 twin turbo was struggling for power on hills, its just that Toyota had calculated the lesser effort of the lower gear was resulting in better economy. That’s how they manage to get 12L/100km (though I’ve not heard many others can from normal driving, another subject). So often some savings can be made from working the vehicle less and pushing the engine less with leaner AFRs, noticeable by less black smoke on the front of the van.

My view in a nutshell?
Yes, drop a gear, manual or auto, under high workload.

Chris Blakemore is owner operator of FNB-4WD in Mt Barker, South Australia


AFR’s (Air Fuel Ratios)   EGT’s (Exhaust Gas Temps)

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