Because, for both the NA and SC X-308, the transmission uses fairly expensive fluid, I am interested if anyone has actually had a transmission that went from not working to working (not just the little "it feels better kind of improvement") after just changing the fluid. If so, do you know if the fluid wasn't just low to begin with?

I suspect it is almost always better to save the cost of the fluid change for the real needed repairs if you can actually detect a transmission problem, rather than even trying that lower cost route. And yet, "conventional wisdom" seems to be that a fluid change might fix it.

 

Hi Ross,

That's a great question!

When I changed the transmission fluid in our '93 to Redline D4 ATF for the first time, I couldn't believe the difference. I had not realized how much our torque converter had been slipping. The old fluid didn't look bad, and I always kept the level up, but after a lot of miles I decided it should be flushed. A fellow XJ40 owner had recommended the Redline D4 so I gave it a try and was amazed at how much better the torque converter locks up. I suspect this is due to the higher viscosity index of D4 (which is designed to replace Dexron II/III) compared to the Dexron VI or Dex/Merc I had previously used, which claim to be backward-compatible for Dexron II/III but have the lower viscosity index common to all "modern" trans fluids. BTW the gearbox in our '93 is the same ZF 4HP24 that's in most of the X300s. Not a direct comparison to the X308, and I can't say whether the old fluid just had broken-down molecules or the wrong viscosity to operate properly, but for what it's worth, there you go.

Cheers,

Don

 

Grant Francis swears by changing the ATF ailing auto transmissions. In his at least.

The Merc transmission is quite happy with Valvoline Maxlife Dex/Merc which is
dirt cheap. The suitability was mentioned in a Mercedes training manual.

The BMW guys running 5 speed ZF's like the same fluid and strip the shelves of it at
Walmart.

 

Well, one of the differences in transmission fluid is the friction enhancing additives, as I understand it. Thats how the "universal" fluids some shops use are supposed to work. You put in the fluid mixed with the correct cocktail of additives.
Plums:
Are you saying the Beemer guys are using Maxlife on a ZF HP24? That it works fine would not surprise me, but I would rather someone else did the testing!

I think Grant has an XJS and a X-300. I did not know either of them could fail a transmission!

 

We have a BMW 3-series and based on my research on fluids for our car, some BMW guys have reported success with Maxlife Mercon V and Dex/Merc in the ZF 5-speed autoboxes. Esso was the manufacturer of the OE fluid for those transmissions. Valvoline claims that their Maxlife Dex/Merc meets some BMW standards, but as far as I know, neither BMW nor Esso have agreed with that claim. Our '04 325i actually has a GM 5-speed box and the correct fluid is good old Dexron III (which does contain friction modifiers). Here's a bit of trivia: the friction modifier in the original Dexron was sperm whale oil.

Cheers,

Don

 

No doubt "low" fluid levels can cause problems. But automatic transmissions do rely on a certain coefficient of friction amongst multiple clutch packs to operate properly, so its reasonable that a breakdown of fluid (high mileage or extremely abusive conditions) could cause problems. The only time I've seen anyone successful in fixing a transmission by simply changing fluid was on a TV episode of Wheeler Dealers and I believe it was a Porsche they were working on.

 

Grant also has S-Types. Two of them. His and hers.

Regarding the use of Valvoline Maxlife Dex/Merc in the Mercedes W5A580, I have
seen the official Mercedes training manual page listing it specifically. Been using
it for 3+ years in that transmission without problems.

Regarding the use in BMW's, I mentioned it because it happens to be the same
fluid. Someone else is testing it ... the Beemer crowd .. and they are far more
numerous than the Jaguar crowd. There is life beyond JF.

Given that the fluid is CHEAP, no problem trying a change first.

 

I have used, gulp, Walmart's Super Tech High mileage ATF in the XJ8. Just over $2 per quart IFAIR. At the time I was careful to check that the oil met basic specs. (Mercon V?).
I know of one well regarded transmission shop that uses it.
Original Esso oil was medium dark @ 120k mi and 8 years. No problems after 7 years. No change in shifts after changes.