We had a wonderful tour of Marin and you can read about it elsewhere in this issue. Check the calendar for coming events; People's Choice on the 18th and Jaguar Corral at Sears Pt on the 31st. A big welcome to new members Jerry and Julie Doyle and their Series I E-Type, Christopher Howard and his 02 XJR, Trent and Henrietta Moseley and their 04 XJ8, and Paul Vrtiak and his Mark X and 95 XJ6. I'm looking forward to meeting all of you at one of our events in the near future.

Many of you who have late model Jags have been asking about when and how the trans fluid should be changed, because there is no dipstick and the transmission is "sealed for life". Yes, it's sealed until it dies, but you can do something to put off that death and save yourself a bundle in the process. Read my column on our website, www.jags.org, explaining what Jaguar was trying to accomplish and why, or just think REAL hard about having that trans fluid changed around 75 thousand miles! For the past decade or so Jaguar has been using the ZF automatic. According to various sources this is a sealed transmission. It is not to be opened because it has a proprietary fluid in it that will last the life of the car, etc, etc. Yet I hear stories of these transmissions crapping out at 100 to 130K miles. Since modern engines with regular oil changes using full synthetic oil can last 250K miles why should you have to rebuild the transmission at half that distance? In the 70's and 80's Jaguar automatics (Borg Warner) typically went belly up at 60K miles. But that was a long time ago. Auto trans technology has made as much progress as tire technology. We should expect an automatic to last the life of the rest of the drivetrain without repair.

Do automatics exist that can run 250K miles and more without rebuild? Yes. I have a Ford work truck with the big 4 speed OD automatic and lockup torque converter. It spent the first 100K of its life towing a trailer and a boat in and out of salt water on Puget Sound. It now has 230K on it and shifts smoothly right on computer command and it easily pulls an 8000 lb load up a 30% grade without slipping. Last November it crested the back side of Donner Summit (the steep side) at 90 mph without any slipping from the lockup converter and no overheating. The outside temp was 60 degrees F. This transmission has a factory installed deep pan for extra fluid capacity and an auxiliary cooler mounted in front of the radiator and air conditioning condenser. I have changed the fluid and filter every 50K miles. What I find is a partly clogged filter, a little metal (steel) on the big magnet and about a teaspoon of black gunk in the bottom of the pan. The fluid has turned from a bright red when new to a burgundy color with hints of gold dust (actually bronze). After the fluid change I notice better shifting (less hesitation esp. when cold or very hot) and crisper lockup of the converter.

The biggest enemy of automatic transmissions is heat. When the fluid gets too hot it doesn't lubricate properly and its friction additives break down. Acids form, some of the fluid carbonizes and the synthetic rubber seals that make it possible to build pressures as high as 250 psi receive abnormal wear. In the presence of acid some of the dissimilar metals (steel, aluminum, bronze) in the tranny act like a battery and sacrifice themselves. Plastic parts are the first to be deformed by heat, next are the aluminum parts and lastly the steel parts. The clutch interplates are made of thin steel. They burn and warp when the fluid is too hot. By the time you are warping these plates you have cooked a good part of the rest of the tranny. Every time a transmission shifts or a converter locks up there is some slippage. A micro-minute amount of clutch facing is sacrificed. The rubber seals in the hydraulic system that applies pressure to the clutches have to move in their steel and aluminum bores. Some infinitesimal amount of rubber must be worn off along with a few molecules of steel and aluminum. All this goes into the fluid and gets circulated through the system. The filter traps most of it, but since some of the contaminants are smaller than the molecules of the fluid itself some of them go along for the ride and do damage to every part they come into contact with. It's a snowball effect. I could wax poetic for pages and pages as the transmission destroys itself, but the upshot of all this is obvious.

CHANGE THE FLUID! You also have to change the filter because it will be partly clogged and could prevent the trans from building full pressure which would lead to clutch slippage, which would lead to accelerated wear, which would lead to . . . a big hole in your wallet. Be very careful that exactly the right amount of fluid is added. Even a half-quart too little or too much can ruin a transmission. Without a dipstick this can be tricky. You need to catch and measure the amount of fluid drained and put back exactly this amount. Expect to pay about $15 a quart for the right fluid. Filter and gasket sets typically run $20 to $40. What about synthetic fluids? The fluid in that ZF is synthetic. Just like synthetic engine oil, synthetic transmission fluids have the advantage that they breakdown at higher temperatures, flow better at lower temperatures, are less affected by acids and form less ash because they don't carbonize as easily or as much. Manufacturers of synthetic fluid claim that their product will last 3 times as long as the mineral based stuff like Dextron and Mercon. If you are dealing with an older transmission be very careful about selecting a synthetic fluid. Make sure that it meets all the specs required for your transmission. Some synthetics are designed specifically for racing. They have no slippage additives, they have no acid neutralizers. They aren't made for longevity; they are made to squeeze out the last bit of performance so you win the race. The hell with the equipment.

So how often should you change the fluid? To quote, "Your mileage may vary depending on you style of driving and other conditions beyond the manufacturers control". When a trans is young it can go longer between changes than when it is reaching the end of its life. Be aware that draining a transmission is not the same as draining an engine. You cannot drain the fluid on a modern torque converter. If you are dealing with an older transmission and you are changing from a mineral based fluid to a synthetic you should change at least 90% of the fluid which means that you will have to have the services of a machine that replaces the fluid in the converter. Manufacturers that do recommend fluid changes claim it isn't necessary to change all the fluid. Changing the fluid that's in the pan will renew the additives required for proper clutch functioning and acid neutralizing. Since the trans started life with a full quota of new fluid and it's only getting a partial trans-fusion (no pun intended) I have to assume that the transmission is overdesigned (like the rest of the vehicle . . hmmm). Are you as confused as I am? All I know is that my '84 XJ6 went 123K miles on the original trans with no work beyond fluid and filter changes (it was still shifting fine when I turned it in for a pollution credit) and I will change my truck's fluid at 30K mile intervals from now on.

As I reflect on the above an intriguing question comes to mind. "Light" duty diesels like my Ford truck are known to go up to ½ million miles with proper maintenance and minimal repairs. There are authenticated cases of the automatic transmission going the distance with the engine. If a ¾ ton diesel truck that weighs 6000 lbs sells for $50K with every luxury option known to autodom can go ½ million miles, how many miles should you expect your 4000 lb, $80K luxury car to go? 6/4 X 8/5 X 500K = 1.2 million miles! Just think of the resale value of such a Jaguar. The first car that became known for true reliability and longevity was the Rolls Royce Silver Ghost of 1907-25. Priced one of those lately? Please mail me your experiences with sealed automatics; the good, the bad, and the ugly.

jtech "at" jags.org