I have seen this topic hashed out in several posts over time, but not recently. Mercon SP is available through O'Reilly Auto for around $4.59/qt. That's a considerable savings over any other brands I've found that are specified for the ZF 6HP26, in Jaguar automobile applications.

I learned about Mercon SP watching Rev Sam's youtube video chronicling his change:

My take is this: It's the same tranny, in all of these different manufacturer's vehicles, Bimmers, Lincolns, Jaguars, etc.. How can it be that just because it's in Jag clothes, that the trans needs Jag approved/Jag specific fluid to perform and remain reliably in service? That seems a preposterous notion.

I found the pan/filter/gasket on Amazon for $78. 12 quarts of SP @ $4.59 is under $60. Pan bolts for $2 ea., and I arrive at a pretty affordable fluid swap. What are your thoughts?

 

How much is the ZF LifeGuard?

That seems to be the current hot recommendation.

 

I didn't have a chance to direct my mechanic who recently rebuilt my 6hp in the xk8 to use ZF Lifeguard6. It was not until I got my invoice, that I found he used Castrol Synthetic. He's been working on ZF tranny's for years, and says this is what he always uses. Its working great since he finished it, no difference at all from what I can tell.

 

That must be the Castrol Multi-Import ATF then?

 

I believe that is what Joycesjag used in his 2005 S Type 2+? years ago, and still running strong.

 

Correct Norri.

Its even a mix with the LifeGuard6. I did the sleeve replacement NOT a full flush. I believe I put in about 7 quarts of Castrol Multi Import.

2+ years and still no problems.

 

I went the Mercon SP route as well. So far, so good. I expected the Mercon SP to be a brownish color, but it was red like other transmission fluids.

I am amazed that you got the filter pan for so cheap. I will have to check amazon to see this deal. The screws were cheapest from gaudinjaguar.com.

Here's a tip, consider puttting the front of the car on ramps and the rear on jack stands. I tried jack stands in the front and the car slid off. Not good.

Another tip, after you fill the first time and start the engine, do not stop the engine until you are finished. I did this and lost 1.6 quarts draining back. Do shift the transmission through all gears, braking for each shift. And definitely use the parking brake before shifting from D to N, R, and P.

Just because the rear wheel you can see is stationary, doesn't mean the one you can't see isn't turning.

 

I don't know if you have it in the States, but I took chances and used:

RAVENOL ATF 6HP Fluid - Items - RAVENOL UK Online Shop

which is very similar in color and feel to the original. So far so good.

 

over the last several days, O'Reilly's raised the price of Mercon SP to $5.99/qt. Auto Zone has Castrol Multi Import ATF for $6.99/qt. Those seem the lowest prices for applicable ATF for the 6HP26

 

Here is the transmission filter pan at Amazon.
$80 with free shipping.

 

I thought "hey, maybe ATF is a bargain on Amazon". Sure enough:
Comes out to $5.09/qt. That's a smokin deal. One could order both the pan/filter/gasket and 12 qts. of fluid from Amazon for for less than $150.

 

I bought all my stuff from the ZF dealer in California. The CTSC - ZF Parts Here is the link. The others are probably fine too but I was sure with these to get the right stuff and I spent $380.00 for 7 litres, the ZF brand pan/filter, the sleeve, and 4 bolts. I did mine about a month ago and I recomend buying all 21 bolts. The T27 bolt heads almost all stripped out. A nice sharp chisel struck with medium force to spin the bolt lefty lucy. Each one came right out. Throw tem way and put in the newer T40 bolts. Job took about 2 hours by a novice like me.

 

Now it's $99. But shipping is free.