My 2018 2500 with 36k miles went into limp mode for 250 miles. No warning lights or other signs. Added 3/4 of a quart of fluid as it was low. Seem to take care of it as went back to shifting normally. Dealership has no ideas on where the fluid went or why it did what it did. Or even if the addition of the fluid did any help. It does seem to lag on the 3 to 4 shift now. Tech said the fluid smelled a little burnt. But not able to tell for sure and didn't want to flush the old out. They want me to bring it in next time it happens. I was unable to the first time or I would have. Any ideas?