Need to top off the PS in a 2006 6.0 F-250. I thought the fluid should be Mercon V. The Ford Parts guy at local dealer speculated it should be Mercon LV. It seems nearly all of the Mercon fluids are not interchangeable. I'm not so sure that I trust the opinion of the Ford parts department guy. Should I?

 

I'm not sure of answer but just went through a similar issue. Changed out oil in transfer case on my 2005 F-150 the other day. Went to dealer and he said I could use Mercon V but "it says not to use it on transfer case on the bottle", lol. I said if it said not to use it I'd rather use what is spec. He said he'd have to order some "transfer case fluid". OK...

So I looked in owner's manual (lol) and it called for MERCON for transfer case and MERCON V for tranny. Went to the local auto parts store and read the back of all the labels. Ended up buying Mobil One synthetic ATF Multi-Vehicle formula. It said on back it meets or exceeds specs for MERCON V and recommended for applications calling for MERCON so I went with it. Not sure if it said anything about MERCON LV though.

I'd check your manual and see what it calls for...

 

owners manual says "Mercon"

Mercon V replaces mercon and is now fully backwards compatible. (this was not always the case, but is now)

that being said, it wouldn't bother me a bit to go to the store and buy a bottle of whatever that says "for use in vehicles specifying Mercon". likewise wouldn't bother me to put in Mercon V

 

This whole fluid spec issue is really confusing. Maybe they expect us to obtain a sample, send it to a lab for analysis, then send the proposed replacement in to see if the two are compatible.

The specs may have changed in 9 years (My 2006 build date is July 2005) making the manual's spec obsolete...if that spec is even in there. It may be, but I couldn't find it. Find specs for other fluids repeated in several places, but the book does a gloss-over for the PS fluid. Believe it states that it uses ATF fluid, not PS.

 

Section should be found in index under "Lubricant Specification". MERCON ATF (Automatic Transmission Fluid) and MERCON mean the same thing. My '05 5.4 power steering calls for MERCON (same as transfer case).

 

Thanks Mike. That's what I'll do. Somewhere on WWW, a table differentiating the various suffixes following "Mercon" ought to exist.

 

cgrutt's suggestion for Mobil1 ATF is a very good one.

i have used this in the past and it is a very good fluid. if you can swallow the price tag, i think it is a top notch product.

i would have zero reservations using mobil 1.

trying to remember what i did on my explorer .... i think i just used walmart's supertech mercon/dex3 fluid. i used mobil 1 in the transfer case, but i think i just put the cheap stuff in the power steering.

 

I have used Mobil 1 syn grease for a dozen years. Mostly on my tractor, but also on my Expedition & camper. Worth the cost.

 

is it bad if power steering fluid is used?

 

It'll eat through the seals and leak like a sieve...

 

I am personally to afraid to add Mercon V to my 4r100. I am using regular Dex/ Merc (just did a pan drop/filter change, not a full flush). I personally feel that ford could care less what I put in my 10 year old transmission because its out of warranty, they would just rather I buy mercon V from them.

I did do synthetic Mobile 1 in the transfer case though. I do not like the idea of mixing fluids (waste of money too) So I would top off the power steering with whatever came in it factory. If it said use MERCON, use generic DEX/MERC. If your doing a full flush, use Synthetic. Also consider one of those magnetic filters.

When I did hydroboost on my Jeep Cherokee I used the Amsoil brand synthetic power steering fluid. Good stuff should last a long time. Is there any reason why you can not use power steering fluid in these trucks?