Hi,
It's says online the the tranmission guage is supposed to read between 175° to 225°F. After driving my prostar nearly 60 miles it crept up to just around 115*F. Does the gauge need replaced, and until then how may I monitor the temp?
Was this bobtail or with a trailer?
This time of year, that sounds normal to me... It is cold out everywhere, 150 under a load is normal right about now, unless you are up in the mountains pulling heavy. Then, 200+ is not out of line. I think you are fine, especially only going 60 miles, again, sounds normal to me.
I'm bob tailing.
Btw, while we are on top of the board, the place where I got the truck from used synthetic mobil delvax extreme 10w-30...
It's a Cummins engine and rotella T needs to be used... What do I do now, go back to rotella T after 12,000 miles or stick with what's in the engine now?
Bobtailing you’re barely working the tranny. 115 degrees is fine
Generally you want lower oil temps as a goal, oil (as far as I understand it) breaks down faster the hotter it is.
run the syn out switch to your choice of oil + gallon of gear lube call it a day.
Everyone I have seen run full synthetic on an ISX has had valve cam issues. - this is because either they use 10-30 (too damn thin!) or they extend oil change intervals (+ bypass filter system) like a fool and it eventually repeatedly wipes out the cams.