I know in some of Scotty's videos he talks about very low viscosity engine oils like 0w-8 and others, and the fact that using some higher weight oils may be allowed under certain circumstances. I bought a 2024 F-150 with the 10 speed transmission, and it requires the ULV (Ultra Low Viscosity) transmission fluid. I'm planning to change the fluid more often than the manual calls for, mainly because of what I've heard from mechanics. What is your view on Ford moving from the LV to the ULV trans fluid, and would it extend the life of the trans if the LV were used instead of ULV? Thanks
No. Always use what the manufacturer calls for, and perform regular transmission fluid changes. I'd probably say every 30-40k miles. Those transmissions are pretty much a crapshoot as it is. GM and Ford collaborated on it and it was so poorly developed and constructed, both Ford and GM say they will never work together again.
I'll give you a bit more insight into why your idea is bad, though. The transmission's hydraulic pump is very sensitive to viscosity changes. If you put heavier fluid than spec into that transmission, the transmission will not shift properly, or even at all, depending on how viscous the new fluid is. The transmission needs ultra thin fluid to speed up shifting performance. Also, not all of the fluid comes out of the transmission when you drain it. There's still lots of fluid in the torque converter, and dropping the pan only takes around 50% of it back out. You will very quickly find yourself in a rat's nest if you were to start the truck after switching to the heavier fluid.
