Does anybody no why the newer 4R70W's can not run regular Mercon? My only guess is they went to a different seal of material type some where. I know my tranny calls for Mercon but everyone says to flush it and refill with Mercon V to help with shudder problems.

I have been looking at every store I go into that might have ATF. Tonight at Pep Boys they had Mobil 1 synthetic , off brand, and valvoline durablend synthetic blend. I like Mobil products but do not like that it does not meet Mercon V specs and it's price (5.99), didn't even check the off brand, and the Valvoline (2.??) which I do not like the brand it does meet the specs I want and is cheaper. At work I can get Havoline Mercon V cheap (2.29) but I want something that is synthetic and will provide the best benifits.

 

KYFordfreak: I wouldn't worry about getting synthetic or not. The Castrol I got is semi-synth and affordable so I bought it. If you haven't seen my website instructions check it out:

http://members.shaw.ca/pferlow/transmission_oil.htm

There's not too much to see when you open the tranny (pan). It's basically this flat type surface with all kinds of bolts and nubs and rivet thingys all over the place. The filter pops off and on easily. Remember to pull the old filter's rubber seal out of the tranny before installing your new filter/seal.

Even if you can't find affordable synthetic it's no big deal to open her up every two years and drain/refill/filter and it should be ok with regular mercon V.

Tip: The two bolts on the rear of the tranny pan are harder to get at especially if you have the front of the pan loose and tilted down. I sloshed the excess oil out of the pan by loosening the front and side bolts and moving the pan up & down, unfortunately this movement let the filter drop into the pan and I couldn't push the pan up all the way to easily remove the rear pan bolts.

 

The only full synthetic that I know of that meets Mercon V is Amsoil. You can make your own decision about that My truck has run with the Valvoline Durablend ATF since 60k, I'm now at 145k and absolutely no problems. I change fluid every 30,000 miles roughly.

As far as the brand goes, go with what you trust. I wouldn't worry about the full sythetic part, but thats me. Good luck...

 

Thanks guys, just wanted everyone's thoughts on the matter. Nobdy seems to know more or give better info than the people on this site, not even top mechanics I've trusted for years. I will probably just go with the cheaper Mercon V or a blend just in case it doesn't sove my problems and it all has to be dumped again soon. I was thinking with as much as these trannies hold I would have to finace a loan just to buy all the fluid if I was going synthetic.

Thanks for the tip on the pan. I did notice it looked to be an already tight fit on the back pan bolts because of the cross member. I guess I need to just go buy the stuff and get this job over with. I'm debating on what my problem is and if I drop the pan if I should install a Transgo shift kit. The smart thing to do would be to change it out, see if it helps then do the shift kit but that would be the expensive option.

 

Has anyone used Mobil 1 ATF instead of Mercon V?
I know it's not rated for Mercon V appications - but why? If it's superior to Mercon or Dexron III, what harm could it do to a transmission that was running Mercon V? It's fully synthetic. Could it be that it's incompatable and will screw up the seals or something? I'm just wondering if anyone has done it.

 

Nobody is really sure of the Mobil1 atf. Don't know why. Best probably to send an email to Mobil and ask them. I wouldn't use it if it doesn't have a Mercon V rating.

But, it's your tranny, not mine so do what makes you feel good.

 

They do say that Mobil one is mercon compatible but nowhere on the spec sheet do they mention Mercon V compatibility.

Check it out for yourself Mobil one ATF spec sheet