Transmission fluid
 

Ihave a 98' f150 5.4 with E40D Tranny, Looking to change the fluid this weekend. I purchased Valvoline high mileage dexronIII/Mercon fluid with the lube guard in the red bottle. I'm getting conflicting opinions about using the dexIII/merc vs.MercV.If MercV is better because its a synthetic,why can't we use MercV in Mercron applications.Could be a stupid question, but I need to know.I want to use the best in my tranny.90,000 plus miles no problems.

The best MERCON fluid is Mobil 1 synthetic ATF. It is the correct fluid for your transmission.

Ford says to not use MERCON V in an E4OD, it may cause damage.

Casey

Bought my 97 Expy with E40D tranny with 83,000 miles. I immediately changed the tranny fluid to Amsoil Universal ATF which meets the Ford specs and noticed a fluid temp drop on my gauge. Shifts were slightly crisper but not like a shift kit or other mod. The mushyness between 2 and 3 shift was decreased but not eliminated.

Tranny fluid
 

Thanks for the info guys. Iwent to Pep boys and looked at Penzoil which had a Merc/MercV rating. Mobil 1 covered everything, and Castrol. No amsoil close by in New Orleans.Thanks again

anytime.