4Runner: Dexron II/III ATF for PS. Mercon V OK?

[nobb]

Recently, I loaded up on ALOT of Mobil 1 Synthetic ATF because Walmart.ca had a closeout sale. This stuff is rated for Mercon V, so I was going to use it to service the ATF and PS in the Fords in our family fleet.

My 1998 Toyota 4Runner calls for Dexron II/III for the power steering fluid and I am wondering if it is also ok to use this Mobil 1 Synthetic ATF in this application? I'm confused because the spec sheet says it "meets or exceeds Ford Mercon V", but the statement seems to suggest for Dexron II, then it's "of the following quality level according to Imperial". It also does not reference Dexron III specifically, but rather IIIG, IIIH.

http://lubes.mobil.ca/canada-english-lcw/automatic-transmission-fluid_mobil-1-synthetic-atf.aspx#

I'm confused as to how one ATF product is suitable for Mercon V, but also older Mercon and Dexron II/III applications because the other ATF brands I see on the store shelf usually make a distinction that their products are not interchangeable.

It's starting to get hard finding Dexron II/III stuff, so in general for the future, is it ok to use Mercon V type ATFs on the power steering of my 4Runner? This also has the benefit in that I can consolidate and use the same fluid on my Fords as well.

Thanks!

 

[69GTX]

The Mercon V is basically an improved Dex III / Mercon product. My 1997 Lincoln got Mercon, the 2002 calls for Mercon V. Nothing different to me between those two transmissions/transaxles except that the product was improved, or the license was expiring. The M1 ATF is a top quality product with an add package stouter than most Dex III's. My 1999 manual transmission calls for DEX III (G/H) but M1 ATF is considered a better replacement fluid for most of those Tremec transmissions. I wouldn't have any problem using the M1 ATF in my 2002 that calls for Mercon V as both have similar viscosities of 7.0-7.5.

Where it gets confusing is something like MaxLife ATF with a viscosity of 6.0 that claims to be suitable for Dex III and Mercon V. The Maxlife is more sheer stable and will hold in the 5.5-6.0 range, while most Dex III's will sheer down into the 5's over time (ie over 10K-20K miles). If you use what's specced you can't go wrong. Commonly found Mercon V approved ATF's include Walmart's SuperTech Merc V and Castrol's Transmax Merc V. Most of them just claim to be "equivalent" to Merc V. I'm not sure I believe that Maxlife ATF can be a low, medium, and regular viscosity ATF all at once. Supposedly all the Mercon V's are at least semi-synthetic where the original Dex III's were basically conventional.

 

[nobb]

Thanks for the quick reply!

So there shouldn't be any seal compatibility issues with this product in mixing with the old stuff that's currently in my power steering correct? I'm just doing the turkey baster method as it's not feasible to do a full flush of the power steering system.

Since I'm using this on an older 4Runner, preventing leaks and maintaining longevity is my main concern. I'm assuming power steering systems probably aren't too picky on viscosity as it is just a simple hydraulic loop.

 

[69GTX]

Using my 1997 vs. 2002 Lincoln as an example. It upspecced to Mercon V on the trans fluid. But remained Mercon for the PS fluid. I currently use Mercon V in the PS fluid....and did several PS "turkey baster" feed and bleeds over the past 2 years. No ill effects noted, nor did I expect any.

Valvoline and others still make a conventional Dex III fluid so I don't see it going away too soon. And the Mobil 1 ATF is essentially a synthetic DEX III with a beefed up add package. Similar quality synthetic DEX III ATF's are made by Redline (D4), Amsoil (ATD, ATF), Honda, and Royal Purple.

 

[SwampSurvivor]

It would work for your PS fluid and transmission just fine.

 

[JMJNet]

The 90s Toyotas are not very picky in terms of PS fluid, you can use any flavor of Trans fluid Dex III/Mercon variety.