trans help

[tnfastbusa]

what is the best trans fluid to buy for a 99, 7.3 auto

[bad_blue_oval]

If you want to upgrade form Mercon to Mercon V, it is a step up. If you want to go all out, I would suggest AMSOIL. It is a full synthetic. Runs about $80 for a 2 1/2 gallon container. But if you are running regular Mercon and dont wanna spend the money for full synthetic then Mercon V is great. I believe its a semi-synthetic, but will pro-long the life of your transmission.

[tnfastbusa]

trucks got 167,000 miles should i change the filter too

[bad_blue_oval]

To be completely honsest, adding semi-synthetic or full synthetic can hurt a high mileage transmission. Why do you want to change fluid? If you just wanna change fluid for maintenence then drop the pan, replace the filter and refill it with plain old Dexron/Mercon fluid.

[tnfastbusa]

thanks

[NCHornet]

Sorry, but just dumping the pan isn't a fluid change, all you are doing is mixing some new fluid with the old crap!! You need to flush all the old fluid out of the TC, cooler and lines as well as trans pump!! The pan will hold about 7-8 quarts, your sytem capacity is around 18-19 quarts. Do the math.
Also the only ATF you should use is Mercon/DexronIII this is what the owners manual says, and the owners manual says specifically not to use Mercon V. Please don't bring up that TSB where Ford all of a sudden says Mercon V is ok to use. Nothing has changed. Do a search for ATF, you will find where I have discussed this often. You can also find the proper flush procedure for your trans. If you can't PM me and I will tell you how to do it in your driveway.

NCH

[bad_blue_oval]

I realize that it does not do a complete system flush. We can go round and round about this, as many of the technicians in this area do... My experience has been that routinely changing your filter and refilling is better than a compete flush. As far as using Mercon V... It is a semi-synthetic, so it can cause porblems in a high mileage vehicle, like this one. But if you get a remanufactured transmission you are money ahead using the Mercon V. Regardless of what the dipstick says.

[NCHornet]

Reman is the key word, if he still has the stock trans than Mercon V should not go in the trans, period!! Anytime you change all fluids it is far superrior to changing half of them. I understand what you are saying that under certain circumstances where people go way to long between flushes that doing a flush can cause failure, but these are few and far between. Regular full flushes are always better, than mixing 7-8 quarts of new fluid to 10 quarts of old fluid.

NCH

[bad_blue_oval]

My problem with flushes is mostly the shops that sell them. They pay no mind to mileage, fluid condition, and most dont drop the pan to inspect and replace the filter. We have had customers try to burn us a couple times, lying about not having a problem and wanting a flush. Then if you do it they come back 2 weeks later and pull the old "Ever since you guys...." bull****. So ya, we are on the same page then. Just alot of shady places out there lookin to earn a quick buck and they dont care about the customer.

[tnfastbusa]

well i changed it and i used 6 1/2 Dexron/Mercon fluid exxon high mil and the fluid that come out looked new and the filter did also so the old owner must have serviced it