Cindy Wood

Unfortunately we had to drive just short of another 250 miles to find a mechanic who knew transmissions. He determined we were three quarts low!!! He didn't have any experience with this truck/transmission but found a small sticker on the transmission, so small it was unreadable without taking a picture of it. It initially didn't make sense. Then after some research we found that in order to check the level you have to heat the engine to the temps in the sticker. Cycle through N,D,R,P, leave the engine running and open a plug on the bottom right forward area of the transmission. If fluid drips out it's full, if it drains out, it's too full. If nothing comes out you need to fill until some fluid starts to drain out. What I'm not sure of yet if the plug is the regular drain plug or a separate plug. Have go get under the truck and see for future reference. The mechanic devised an ingenious device to fill the trans. He fashioned a plug to fit into the fill hole, cored it out so a tube could enter it, then made a funnel cap to screw on the trans fluid bottle and put the trans fluid through the tube and into the transmission. Took three quarts. I think the U.S. Mechanics just arbitrarily put in 6 quarts cold (or maybe got distracted and put in less) and never checked the level. Cost was $355.00 The guy in Mexico spent probably twice as much time on the truck trying to figure it out and charged me $15.00. To think....I had the service done in the U.S. so it would be done right! Fortunately we did the off road trek or we would have never known there was a problem, maybe until something burnt up. All is well, we made it to our destination, albeit a bit late Thank you for the help and insights!

Thank you for the insight. Driving on pavement the temp is normal, even up long steep hills. No slippage, Also, no it wasn't' sand slippage. RPM's up to 5000 and no forward motion or tire spin. Let off accelerator and when slowed down drove normal for a bit then repeat. Put it in manual and was able to creep back to pavement. Not a single issue on pavement. Still have a 2 hr drive this morning to a supposedly good mechanic. So far so all good driving on pavement, almost 700 miles on pavement and no issues. Drove about 550 miles on pavement after trans service and didn't even know there was an issue until hit heavy offroad conditions. Have driven another 150 miles on pavement since and have another 150 to go to a good mechanic. So far so good. Weird stuff.

Thank you Jettch1! Hopefully that's it. I'll find out tomorrow. Still...anyone know how much less to fluid to put in if just change the fluid without dropping the pan? Thank you!

I'm traveling in Baja California. Just had the pan dropped and transmission filter/fluid changed up in California. Driving on pavement transmission acts normal, but after about 10 miles of off road driving in heavy washboard, the tach started revving to 5000 rpm and no forward motion. The worse the washboard got, the worse the problem. When driving and switching gears manually it seemed to work OK. Only had problems when shifting automatically. Constantly revving. I worked my way back to the pavement and once I reached the pavement all was working fine again. My best guess is that when they changed the fluid, they didn't add enough and agitating it off road is allowing air into the lines? Of course no way to check how much fluid is in there (at least that I know of). Tomorrow I plan to drain the fluid and see how much there is and replace with the correct amount. Vehicle is a 2020 Silverado HD. 6.6 gasoline engine. My questions: Anyone know how much fluid I should put it without having dropped the pan? Can you think of any other faults that could be causing the transmission to slip only offroad? Thank you for any help you might be able to offer.