OK, sorry I have searched all over this site, great info but here is my ?
1993 F150 XLT-5.0-AT(4EOD)
Just purchased, previous owner had top end rebuilt (heads, injectors) and trans repl'd 10K ago. Total 151000 OD
Is Ford Tranny flush good enough and is the DEX lll or 4 they use synthetic?
Is it too late to put in syn motor oil 10-30W since the bottom was not rebuilt or just use conventional 10-30W or Ford Syn blend?
THank you

 

You can use syn oil if you like. I do recommend going with 5w-30 instead of 10w-30, though.

GMs use Dexron ATFs. Fords use Mercon ATFs.

With that being said, E4ODs do not require a synthetic ATF, but they do require a good, robust ATF. In my experience, the E4OD doesn't like no-name ATF. I've tried cheap no-name ATF twice and got poor results twice. The E4OD has a drain plug on the torque converter so you can drain the transmission pan and the torque converter and put about 12 to 14 quarts of new fluid in.

 

So Ford dealer tranny flush with Mercon lll and 5-30w Ford Syn blend would be good start? Seems like high mileage engines don't like full syn, correct?
Correction: just talked with local ford dealer, said all they use in Mercon5 which he said was backward compatible and they use a cleaner first then conditioner after adding fluid, is this correct?
Thanks again

 

It's not an issue of mileage, it's an issue of the condition of the seals/gaskets on the engine.

Typically, if an engine wasn't maintained all that well, the engine will have a bit of a sludge buildup around the seals/gaskets which dries out the gaskets/seals, but yet the sludge buildup blocks the conventional oil from leaking.

When you go with full synthetic, it starts to clean the engine out, which then exposes the bad seals/gaskets and in turn causes a leak.

If the engine has high mileage and is clean and has no leaks, you can go with full synthetic and not have to worry about leaks.

Honestly, I'd give full synthetic a try, but Motorcraft Syn Blend is a great oil, though.

On another note, one thing oil related that I recommend going with on our trucks is a Motorcraft PCV valve instead of any other brand. It might cost $2-$3 more, but it's worth the investment.

 

Mercon V is compatible with the E4OD.

 

Also, as far as methods to change the transmission fluid, the dealer more than likely has a fluid exchange machine to do it.

As far as a non-machine way to do it, pouring a bottle of Seafoam Transtune in it and driving it for a week before draining the torque converter and transmission pan is common. It's what I do.

Also, if your truck is a 2wd drive, you can use a 4R100 transmission pan. It has a drain plug in it and will make life much easier for you when it comes to future maintenance.

 

Any thoughts on tranny oil, convention or syn? Should I use mercon 3 or 5?

 

As far as Transmission Fluid goes, there is no Mercon 3. You're confusing it with Dexron III, which is for GM products. You've probably seen plenty of fluid bottles/jugs that say Dexron III/Mercon.

There is Mercon and Mercon V.

With that being said, Mercon was discontinued awhile back, but Mercon V is what superceded Mercon. However, there are transmission fluids made, which meet Mercon specs, such as Mercon V.

As far as Transmission Fluid goes, I suggest going with a High Mileage fluid or Synthetic fluid. Conventional fluid might be OK if you go with a name brand fluid.

 

Last one, this trans has just been replaced with a rebuild and has approx 11000 miles on it, still use high mileage?
Thanks again
Bryan

 

High Mileage ATF won't ruin anything or void warranties. It's more robust than the conventional stuff. Even if you don't go with the high mileage, go with a good name brand conventional ATF at the bare minimum.

I'm a fan of Valvoline Maxlife ATF in the E4OD. It's synthetic and high mileage. The best of both worlds in my opinion. Very good stuff. And for the record, I have zero brand loyalty. I'm loyal to what works.

However, if you have a fresh rebuild, the transmission should be clean and all you should do is a drain and refill with your favorite synthetic fluid.

On a side note, have you changed the gear oil in your differential(s) yet?