Damage from Dex III instead of Mercon V ?

[ArcticCat]

What would happen if someone used Dexron III in a transmission that required Mercon V?

Would the driver notice any difference while driving? Would the transmission simply have a slightly reduced lifespan (20% or less reduction in lifespan), or would the transmission die within 20,000 miles?

For arguments sake, lets say the transmission is a 2004 Ford Focus with about 50,000 miles on it at the time the Dexron III is added to the transmission (a full flush and refill).

 

[Colt45ws]

Shuddering will probably show up very quickly.

 

[Bluestream]

I would say no damage at all. You would likley noy notice anything

 

[exranger06]

I would at the very least add Lubeguard. The one that "converts" Dex III to Mercon V.

 

[beast3300]

Most of the older Ford apps used regular Mercon (Dex3) and were superceeded to Mercon5. I would say that the transmission would last about the same. However may needed serviced more often.

 

[The motor guy]

Just put the correct stuff in it. NO need to spend 3000 dollars on a tranny if you don't have to. If the transmission still works ok then it should be fine but I would get the other stuff out and put the correct stuff in immediately.

 

[OldCowboy]

+1

 

[Ken2]

A couple of clarifications:

GM's Dexron-III and Ford's Mercon are different products with different (but close) specs. Just about all the aftermarket Dexron-III ATF were blended to also meet Mercon specs. Before GM stopped licensing Dexron-III and before Ford stopped licensing Mercon, these dual products would be licensed by both transmission makers because they passed both test routines.

MerconV is a different spec product again. The latest version of MerconV has been said by Ford to be suitable for all transmissions that called for either Mercon or MerconV. Ford licenses the ATF that is "approved" for MerconV applications, not the fluids that are "recommended" for MerconV usage.

Lubegard green bottle is the supplement said to change the friction characteristics of a Dexron-III/Mercon fluid to meet the needs of a transmission that calls for MerconV.

ArcticCat, if the Dex-III is already in the Ford transmission, just add the Lubegard green bottle stuff. The transmission will perform better.

 

[Y_K]

I had it done once in a CrownVic: mechanic's error. Felt more sluggish. Replaced by Mercon V after 11k miles, as I did not bother at that time. 300k miles later it was fine.

 

[RF Overlord]

ArcticCat, as the others said ^^^ as long as you haven't noticed anything unusual in its operation, it's doubtful there's any damage, but if it were MY car, I would have the party responsible flush it back out and replace with Mercon V, if that's the recommended fluid, at their expense. Who knows what slow-acting long term damage could occur if left alone.