My 2002 should use Mercon trans fluid for power steering fluid according to my manual.

It also states that for the trans, Mercon and Mercon V should not be mixed.

So, my question is if I vacuum out the PS reservoir and put Mercon V in it, will mixing it in the ps system be okay?

 

Yes, no problem. I use Mobil 1 ATF, which is a synthetic universal fluid.

 

That information in the manual was superceded several years later. Early Mercon V was incompatible with Mercon in certain transmissions. The caution against mixing the two types wasn't applicable to power steering systems.

Use current Mercon V or, if you still have some on hand, the "old" Mercon formula may still be used for any vehicle for which it was originally specified.

 

Difference between the two. Mercon and Mercon V is the base oil used and seal conditioners. The original Mercon was a mineral oil and had little to no regard for seals. The Mercon V is a synthetic base fluid with seal conditioners. Mercon from Ford hasn't been made since 2008. In a pinch, you could mix the two but it would be better to just drain the system and use Mercon V in the future. All of the universal ATFs are a Mercon V and Dex III fluid. The specs for each is real close considering the spec was made by Ford and GM in concert with the transmission technology they shared.

 

Thanks for the responses!

My 2002 has the old style steering box and I don't think I can drain it without taking it off the truck. Although I haven't actually looked at it for the purpose. So, mixing may be the only option.

 

Mixing is no big deal as long as it's ATF and not PS fluid. Ford steering doesn't like PS fluid.

 

I use Amsoil ATF in my vehicles power steering. They seem to like it. As with all the vehicle fluids, I also flush it out every couple of years.
If I were in your current situation, drain the reservoir and fill with your choice of Mercon V. Run your steering system through fully to ensure the new fluid is getting all around. After about a week, I would drain and refill again with the new fluid.


-2002 F150: 206,000 miles
-2000 Windstar: 160,000 miles

 

Well Men, today I was in Autozone and they had STP brand and Castrol brand Dexron/Mercon transmission fluid. So, we can still buy Mercon for the power steering and the transfer case. They also had the Valvoline XL 12 transfer case oil that meets the Ford Spec.