Thanks for update and validation on the Mercon SP. We have similar opinions regarding the Mercon SP product. We only did 2 flushes with first one changing the pan.

 

Again, Mercon SP meets the required Shell M1375.4 specs and I continue to believe its formulation is as close to ZF's liquid gold (Lifeguard 6) as anything else you'll find on the market. I run it in both of our Jaguars with absolutely no regrets (they have both been drained-and-filled with it twice now) and I never hesitate to give it a thumbs-up for any 6HP26 that is past its warranty period....

 

OK guys. I got 45,000 miles out of the first MERCON fill. Most of the anomalies I'd had before the swap never came back. The only one that persisted was the slight surging in higher gears when cold and driving slowly (common complaint), but even that was vastly reduced for this entire period.

The only quirk that may have appeared was a recent (last 10,000 miles) tendency for the tranny to kind of ****** 2nd gear when accelerating from a stop.

Today I refreshed the trans with 4 or five quarts of SP (much goes on the ground, so I really don't know exactly what goes "into" the trans). After the initial filling, starting the engine, cycling the gears, and continuing to fill, I "JUST" caught it at the 50C mark. and put the plug in. Be careful about this - if you service a warm car without giving it a couple of hours to cool down, you'll be right at the 50 degree limit when you're finished topping it off.

So because of plugging it at 50C I'm filled to the "Low" mark. We'll see how that plays out. I certainly would have preferred to catch it a few degrees lower. After a little drive to make sure everything mixed well and up to temp I paid close attention to her shifts. The ****** to 2nd gear is all but gone. 3rd, 4th & 5th upshifts are completely seamless. There's an ever so slight nudge into 6th, but nothing to complain about at all. Routine downshifts while decelerating are completely undetectable. I didn't test them, but I'm sure her kick downs are still as quick and predictable as before. She's still SWEET at 215,000 miles!

On the next MERCON service I'll replace the filter (about 100,000 miles) and upgrade the pan bolts. Why those bolts weren't upgraded in 2014 when the shop put the Redline (yech) and new filter in, I don't know, but as usual "I'll" get the job done right when I do it myself.

 

Glad to hear that like all of us who have made the conversion thus far, you continue to be completely satisfied with Mercon SP. No question that it should now be considered the default replacement ATF for any 6HP26 vehicle....

 

Yeh Jon. There should be questions remaining on this. If someone has "Stupid Money" to throw at $40 a quart Jaguar ATF, that's their choice, but my IQ is over 130 - so THAT ain't happening here! - lol.

The drive to work this morning (with temps in the 40s) seemed to show that the cold surging is once again vastly reduced. I'm not sure I'd notice it at all if I wasn't looking for it. I also checked a simple kick-down from 6th to 5th, and as expected it was unmentionable. I eased on the gas pedal and she dropped down with no delay or lurch. Quite nice.

I've got to start a thread on how many miles the 6HP26 goes before failure. Curiosity is getting the better of me.

 

Also have done changes with Mercon SP and no problems at 135K. Just cked E-Bay site and searched for Mercon SP. The replacement listed is still listed a Mercon SP but has a new name along with SP. It is Mercon XT-6-QSP. The container is Red and still lists Mercon SP on label. The description says DIRECT Replacement for the original. FWIW. Expect there are enough of the FORD products on road, they will not discontinue the Spec Fluid soon.

 

The red quart bottles of Mercon SP I have been purchasing from a local Ford dealership since mid-2014 have always had that XT-6-QSP part number on them. My guess is that the formula they are selling now is exactly the same as the formula they were selling back then....

By the way, my 2005 S-Type now shows about 103,600 miles on the odometer and my wife's 2006 XK8 now shows about 112,700 miles on the odometer. Both vehicles are running superbly and I expect that both of their ZF units have plenty of life still left in them....

 

Of course anyone who pays $40 a quart for LFG6 is not being sensible but who pays anywhere close to that?

For all of us who paid a heck of a lot less than $40 and who have total peace of mind my hat is off to you. Especially those that did a complete flush.

 

Latest update on the MERCON SP:

On the last refill I only got the plug back in right as the temp was hitting 50C, so this weekend I went in and topped it off. This time I had someone in the cockpit to cycle through the gears so I wasn't going in and out and up and under. At about 30C at the start she took half a quart more and only dribbled a little out before hitting 40C. I plugged it immediately at that point. I was using a laser thermometer aimed right at the escaping fluid.

Amazingly, the slight morning "surging" that has been ever present for the last 5 years seems to be completely gone. I had morning drives to work with the outside temperature in the low thirties too. I didn't even realize the surging was gone until yesterday. This morning, with temps in the low 50s, I paid particular attention. Nada. Nothing. No matter how hard I listened or wiggled my butt, I couldn't discern a single bit of surging. It almost feels as if something's "wrong" - lol. The slightly abrupt upshift to 2nd gear also seems better, but the jury is still out on that.

My recommendation to all 6HP26 fans: Plug the transmission off right at 40C on a fill or refill.

 

Hi:
Newby here -- I see that the Mercon SP is the way to go for my 2006 XK8, but have found both Motorcraft and Valvoline sources. Back in earlier times, I was quite enamored of Valvoline products. I have never before heard of Motorcraft. The prices are close enough together , so what do our experts say?
Is anyone still paying attention to this thread?

 

Motorcraft is Ford and is a respectable brand. Any fluid that meets the specification should be perfectly fine.

 

Thank you, Charlie!
DY

 

Hi DSY,

I and a few other X350 owners have done extensive research on fluids for the 6HP26, and as of now, the only fluids known to be correct are ZF Lifeguard 6 and the Jaguar branded version sold at dealerships, Ford Motorcraft Mercon SP, and Shell Spirax S4 ATF MSP. Of these, the most affordable and available fluid in the U.S. is Mercon SP. This is the fluid Ford uses in its versions of the 6HP26 used in the Ford Expedition and Lincoln Navigator, among others.

Lifeguard 6 is manufactured in Europe by Royal Dutch Shell. Mercon SP is manufactured in Houston, Texas by Shell Oil Company North America. The only difference between the two fluids is the red dye in Mercon SP, added at Ford's request to help their dealership technicians identify it as ATF rather than engine oil.

Use only the genuine Ford Motorcraft Mercon SP, not one of the many aftermarket fluids whose manufacturer claims to be equivalent to Lifeguard 6 or Mercon SP or to meet the Shell M1375.4 specification. There are many of these pretenders, including fluids from Valvoline, but do not use them. Despite their manufacturer's claims that they meet Shell M1375.4, their chemical properties are incorrect, starting with their viscosity.

For more information than you ever wanted, see this post:

ZF 6HP26 Transmission Fluid Flush DIY

Cheers,

Don

 

Thank you, Don! That DIY is the best note I have read on anything. It will guide me in this new endeavor, and I really appreciate your sharing of it.
Doug

 

Hi DSY

I agree with Don - Other brands might be out there that “might” work, but stick to those we’ve mentioned; especially the Merc SP. I don’t have any information on Valvoline, but I “can” tell you to absolutely stay away from Red Line.