ATF: To change or not to change?

[meborder]

Originally Posted By: meep
pop-ups are easy to pull. it's not the weight as much as it is the frontal area... which they have very little of. On top of that, it's light. And if you are paying attention to the speed ratings of the trailer tires, you'll be under 65. therefore, not critical.

OTOH, 60k is enough miles in my book to warrant a change, so I'd plan for it at some point.

I've seen a good number of Expi's on factory fill at 150k driving fine, so I suspect for daily driving they are overbuilt.


as an aside, and only because you mentioned it, but completely off topic ...

I was actually quite mindful of the speed rating on my trailer tires. they were Kenda LoadStar ST145r12 LRE (10ply) which replaced the LRD (8ply) orignals that blew out on the road.

the original tires ad a 75mph speed rating (Service index followed by the letter "L" indicating the speed rating of 75). one of these blew out on a hot day at 65mph. in all honesty, I'm thinking my father in law didn't check the pressure, and that's whyit failed.

the Kenda LoadStars are advertised as a 65mph speed rated tire (according to etrailer). I ran them at 70mph, but brough my IR gun along to keep an eye on tire and bearing temps. on the road, the tires, rims, and bearings were always 113-117°F, with the ambient temp in the low to mid 90's. checking the pavement next to the tire (when stopped) the tires were running essentially the same as the pavement - within a few degrees anyway. this settled my mind about exceeding the speed rating.

I'm guessing by upgrading to the LR-E tires, I bought some headroom with regard to speed with the increased load carrying capacity of the tire. with the 10 ply rating, the tires weren't so near to the max load as were the 8 ply tires.

I have no reservations running those tires at 70mph. I considered upping to 75, but with two kids in the back and ambient temps in the low 100's (104 at wasta, to be exact), I didn't feel like pushing my luck anymore than I felt I already was.

nothing to do with transmissions, but interesting, I thought ... and since you brought it up....

 

[DoubleWasp]

The terrible speed ratings of trailer tires had pushed me toward just mounting up LT tires instead.

 

[meborder]

Originally Posted By: DoubleWasp
The terrible speed ratings of trailer tires had pushed me toward just mounting up LT tires instead.


a fair enough point, but it does pose a couple problems:

1: not an option for 14inch and smaller sizes
2: generally more costly, and usually requires an upgrade in load range to get the same weight rating.

#2 can be particularly problematic on a 7,000 lbs axle. in a 235/85r16 (most common for that axle rating) an LT tire in a LR-E is only good to 3086lbs, which is not enough. so you either have to step up to a LR-G, which are much more costly, and require 115psi to get up to the required 3500lbs per tire. or you can go with a Carlisle ST LR-E which is good to 3638 lbs at 80 psi and comes with a 75mph speed rating for much less money.

many of the trailer tires on the market now are coming out with 75mph+ speed ratings, so this is much less of an issue than it was a few years ago. I think the tire makers are getting tired of the bad customer reviews and have stepped up their game.

 

[DoubleWasp]

Definitely limited to certain applications only. Not that I'm trying to push any speed records hauling a load, but I don't like operating so close to, or at a limit under those circumstances.

 

[corndogzombie]

Me, I'd change it.
My personal routine is to do a pan drain and refill every 15 thousand. Not a pan drop I keep an external inline filter on so no need to drop the pan and change the internal filter very often. Maybe every 100k or so but that's probably not really even necessary in my case since i added the inline filter when I did the first internal filter change.
Magnifine suggest not dropping the pan for 100k when using their filters.

 

[demarpaint]

Originally Posted By: meborder
Thought id update after the trip.

Pulled out and back with no real issues, but I do think it is time for a change.

I was able to pull across the state in OD with the cruise set at 70mph without any troubles. On the steepest of hills would make it drop down to 3rd. (until, that is until I got into the hills where 2nd gear was required due to lower speeds and 5,000+ft elevations)

What I did notice is that the 4-3 downshift would flare slightly if the trans temp was above 180f. Below 180f, no flare at all. So the fluid might be degrading such that the viscosity is too low as the temps climb.

Mostly the trans ran between 175 and 190 depending on terrain. Outside temps were between 95-104f. And the truck and trailer were both packed full, so I'm happy with the performance,overall.

That higher temp flare makes me think its time to change it out.

Under those conditions the transmission temperatures weren't bad. I agree with your comments about the slight flare, I'd change the fluid.