Originally Posted by thestrangebrew
My F150 usually runs about 203-208 when towing. Ambient air has typically been mid 90s this year so far. On some of the hills, I see it go to about 213, and once coming home recently I saw it get to about 224 going up a 7% grade punching it (I was passing a semi). Stayed ~224 for about 5 mins until we crested and started going downhill. I guess my question would be, how long is too long to run at these temps?
I am no expert... However, ...
I have been told , by a transmission repairman whom I trusted to work on my truck, that for any thing over a few minutes at 225 degrees F
can burn the oil and break down it's lubricating properties. ... IMO 5 min would be max. with regular tranny oil.
Two things to help with this is...
1) use semi-synthetic transmission oil, as it can with stand higher temps.
2) add a larger or an additional tranny oil cooler.
I don't know the year of your truck.... but on older trucks (like mine) high temperatures in the tranny can create high pressure and sometimes that pressure has to be relieved, in my case through the vent on the top of the transmission. When it blew (twice) I thought that I had blown the whole tranny
...but it was just oil spraying out.
Hope this helps.
'07 WildCat 30 RLBS ~ West Coast Edition ~
Trail Air - Tri Glide Pin Box
2000 F350 DRW 7.3 Diesel Lariat 89k miles
Edge programmer, 4" SS exhaust turbo/back
Vancouver Island, B.C., Canada