Aftermarket trans coolers are over-rated, IMO

Get yourself one of these Hand Crank Siphon pump and change that tired fluid every 12-18K miles.

You can't get a Chevrolet, with the Duramax with a manual either. I don't know how they're getting better mileage with an auto either. Its always been that you could get just a bit better mileage with a stick.

my nissan fortunately has a drain plug for the tranny making a fluid change a snap.

A few things...

Your best bet is to look for a user forum for the specific vehicle that you drive. Lots of these are out there, some better than others, but the knowledge base is excellent, and typically includes machanics, etc.

I tow with OD, both with the RV and the Explorers. The only time I change to D is on inclines. You know you have a problem when the tranny keeps shifting from OD to D and back.

I don't think tranny coolers are over-rated at all. Get the biggest one that will fit your vehicle. Heat is a major enemy of auto trannys.

As mentioned, drain plugs are helpful. You can get an aftermarket kit (involves drilling a hole in your pan, may not be for the squeamish).

Hope this helps.

Mike

Why more manufacturers don't do that is beyone me... dropping the pan is always messy! Luckily my F350 has a drain plug as well. My Chevy 2500 did not.

Drain plugs will only get to so much of the transmission fluid. Even if you drain the pan, more than half of the fluid from an AT will be in other places. The only way to really get at all the fluid is to flush the trans, which requires a little pump or gravity feed.

or you change it twice as often like I do...I figure I get about 50% of the fluid out with a drain and fill. I don't want anyone taking my cooling lines loose to have the potential for leaks down the road. Then again, I don't trust anyone to work on my cars other than myself either.

what I meant was that I'd pull the plug and drain, then drop the pan so I don't have to handle a pan full of fluid.

PTP,
I THINK this is the reason. Horsepower = RPM X Torque. Theoretically, it will always take the same amount of horsepower to move your truck + trailer + boats + stuff at say 70 MPH but you can vary the RPM and Torque to achieve that horsepower. The idea behind an OD is that the engine can normally more efficiently develop the horsepower to cruise at interstate speeds (without a load) at lower RPMs and higher torque. The problem is that when you add a load the required horsepower increases due to higher weight and drag. The RPM to go 70 MPH in OD does not change so the torque must go up. This causes two issues. The first is that the engine is probably not that efficient at this new RPM/Torque ratio. The second is that your transmission and the rest of the drivetrain can only handle so much torque before it is damaged. As torque in a gear box increases, the pressure/friction on the gears goes up. If it goes too high the thin layer of oil that is allowing the gear teeth to smoothly mesh gets squeezed out and then you have metal scraping on metal, which is bad. To handle more torque you either need a better gearbox (bigger gears = less PSI of pressure) or better oil/lubrication system. Where I work we recently increased the torque capacities of our gearboxes by 10% just by switching to a better oil. (synthetic instead of conventional) The heat a gear box generates is do to friction. As you transmit more horsepower through gear box it generates more heat. Also, as noted above automatic transmissions, slip under high torque and that generates heat too although it may protect your gears. Your gear box/oil has an optimum operating temperature. If it gets too hot it will cause damage. That is why a lot of gear boxes will have oil coolers. Sorry, to be so long winded and I may be wrong.

It's to get you to replace the filter.