Quote:
Originally Posted by mgarblik
Couple observations about transmission fluid temps. That chart posted is very old. Before full synthetic trans fluid was the norm. So for our old muscle cars using old Dexron or type F dyno oil fluid, staying under 210 degrees is wise. Full synthetic fluids take the chart numbers and you can ratchet up each category of failure 20 degrees minimum. My wife's Jeep has a trans temp sensor you can monitor while on the road. On a long trip recently in 95 degree weather through the mountains of West Virginia, I saw a high trans temp of 190 degrees and a highest coolant temp of 225 degrees F. The fleet of Ford Transit 350 HD vans I work on have no dipstick and no drain on the 10 speed automatics. We have several now with just over 300,000 miles on them. Per Ford recommendations, no fluid changes, no service, no checks. Look for fluid leaks. No leaks, keep on driving. They have temp sensors as well. Seem to run around 170-185 in hot summer weather. I have to say I am very impressed with the 10 speeds. Not a single failure yet. I am sure it will cost $$$$ when one finally croaks.
|
good point on synthetic fluids handling heat better than old non synthetics. synthetic fluid will not break down near as fast as older fluids due to heat or wear/time... but the charts show as you approach & pass ~220 its not the fluid that fails its the internal parts of the trans like seals harden, plates slip & clutches burn out. i dont think any fluid will prevent that at extreme temps. its more of a reference point to indicate what higher temps do to older fluids as well as internal parts.
i have a 4th gen 4 runner & toyota also calls their WS ATF "lifetime" but it most certainly is not, the owners manual tells you to do a full exchange at 100k miles or 60k miles if used for heavy towing or other hard abuse like off roading. wonder if buried in the ford OM there is a stated fluid change at a certain mileage? toyota also has many trans/engines of this era going 300k+ miles, some on original ATF & they all use standard spin on oil filters ... theres a documented tacoma with the same engine/trans as 4runners that hit 1 million miles & was still going strong. modern vehicles are much better built than older or classic cars as far as drive train reliability.