G
glamis_regularOP
2023 Silverado ZR2 6.2, RZR Pro R in the trailer
PrerunnerYuma, AZ28 posts · joined Jun 2025
it is too hot to run Glamis right now so we take the RZR to Pismo for the summer like everybody else from Yuma. 2023 Silverado ZR2, 6.2, 10 speed, pulling a 24 foot enclosed trailer with the Pro R, gear and water in it. scale ticket in Yuma said 7,640 on the trailer.
last saturday, 112 out, climbing the grade on I-8 west of Ocotillo up toward the In-Ko-Pah exit. tow haul mode on, AC on, 55 mph in the right lane. trans temp on the gauge climbed to 228 by the top. engine oil hit 258. coolant never moved. nothing beeped and nothing shifted funny. is 228 normal for that grade in July or am i cooking it. the owners manual on chevrolet.com gives the tow ratings but nothing useful on what temp is too much.
O
ocotillo_weekends
2022 Ram TRX, Hydro Blue, stock
Long travelEl Centro, CA17 posts · joined Jun 2025
El Centro, i drive that grade every week, empty most of the time. it is about 3,000 feet of climb in eleven or twelve miles and it is the hardest stretch of road between here and San Diego for anything towing. there is a reason Caltrans has those radiator water tanks along the shoulder. i see somebody pulled over with the hood up every single weekend between June and September.
228 at the top with a 7,600 pound box behind you at 112 sounds fine to me. you made it up without stopping. the guys with the hoods up are not running 228.
F
ford_tech_marisol
2017 Raptor, Ford master tech by day
Trophy classEl Paso, TX52 posts · joined Jun 2025
fun fact, your 10L80 is the GM cousin of our 10R80, they were designed together, so i see the same numbers on our side. 228 on a hard climb in that heat is inside what i would call normal. where i start paying attention is 240 and up, and anything that sits at 250 for a long time is cooking the fluid.
two things that help. in tow haul, pull it out of the top gears manually on the grade so it is not hunting between 6 and 7, keep the revs up and the converter locked. and if you tow like this every summer, change the trans fluid on the severe service schedule, not the normal one. that is the real cost of the In-Ko-Pah, not the 228.
G
glamis_regularOP
2023 Silverado ZR2 6.2, RZR Pro R in the trailer
PrerunnerYuma, AZ28 posts · joined Jun 2025
did the trip again friday. left Yuma at 4 am so we hit the grade at sunrise with it at 88 out. held it in 5th manually like marisol said, 50 mph, converter stayed locked. trans peaked at 214, oil at 241. that is a big difference for an alarm clock. coming home sunday afternoon at 109 downhill it never went over 190, obviously.
M
mod_kyle_b
2022 Tundra TRD Pro, i-FORCE MAX
ModeratorSt. George, UT44 posts · joined Jun 2025
same story on I-15 through the Virgin River Gorge north of here, shorter but steeper in spots and it is 110 most of July. the people i see in trouble are almost always pulling something heavy at 70 in the top gear with the AC on max. going early fixes most of it. glamis, nice write up, i am leaving this one unlocked for the next guy who searches it.
T
trx_or_raptor_r
2021 Ram TRX Launch Edition
Long travelHouston, TX31 posts · joined Jun 2025
Houston view. our problem is not grades, it is humidity and sitting in traffic on 610 at 98 with a trailer. i added an aftermarket trans cooler to my TRX and it dropped my towing temps about 12 degrees in traffic. on a ZR2 i would not bother if you are only doing that grade a few times a summer and you leave early. sounds like you solved it with a calendar.
