Did you read the thread I linked? <img src="/forums/images/graemlins/confused.gif" alt="" />

Yes. However that failure seemed to be a result of a clogged cooler and hard use and repeated overheatings. It was also a different tranny than what I have. I'm not sure I would consider that conclusive proof that Mobil 1 caused the failure.

I guess I was out to lunch when the 'Alex' procedure was discussed John, so can you enlighten me on what it is?

"Edit"
Never mind I see the post below.

Several people have had the transmission lose OD and in almost all cases were just switched to Mobil 1. Those are some pretty neat coincidences. <img src="/forums/images/graemlins/lol.gif" alt="" />

Also, the trans fluid marked Chrysler ATF+4 OR Hyundai ATF are suitable replacements for Diamond (Hyundai runs Mitsubishi transmissions so its no different than Diamond)

I obviously agree with the consensus (albeit not 'scientifically' proven) and won't be using Mobil 1 in my 89 gen I auto tranny. If someone proves that it's safe, then I would certainly reconsider my opinion but being that I don't drive it daily and probably only need to replace the fluid every couple of years, I probably still wouldn't use Mobil 1. <img src="/forums/images/graemlins/lol.gif" alt="" />

All that said, one thing though is Scott's Mitsu is a gen II and not a gen I. Is the build and design of both the same? Do they use the same internal materials? These are all unknowns to me at this time however seeing Mobil 1 AT fluid's track record with Mitsu Gen I Auto Transmission's I'm just not that much of a gambling man. Additionally with less than 10k driven on my 96SR each year & the track record of this tranny's reliability using regular dino based tranny fluid, I think I'll be ok just using plain old mitsu tranny fluid. <img src="/forums/images/graemlins/lol.gif" alt="" />

Just my $.02 <img src="/forums/images/graemlins/cheers.gif" alt="" />

Just want to point out that I am not trying to say that anyone here is incorrect. Just want to let you know that I value all of your opinions.

I have been all over the internet researching "Diamond SP" ATF trying to figure out what makes it different from other ATFs, if there even is a difference.

What I have turned up so far is that there seem to be friction modifiers in Diamond SP. I say "seem" because so far as I can tell, no real facts have been uncovered in my research, only conjecture and opinions.

What has be a little confused is that the owners manual specifies "Diamond SP or Dextron II or equivalent" those are the exact words used in TWO places in the manual, in the capacities chart and also on page 192.

So.....If Diamond SP contains modifiers, then why would Mitsubishi specifically recommend "Dextron II or equivalent" as a replacement, knowing that Dextron II does not contain the proprietary friction modifiers?

A ton of comments so far all over the internet say use only Diamond SP in these trannys.
The best source I've found so far is this web site.

I am still on the fence about it. But I will flush out the Mobil 1 and get the Diamond SP.

Here's why. My wife has been driving the Monty full time. She likes it. She is not into cars and can't detect if something is amiss.

If I were piloting it full time, I'd leave the Mobil 1 in there and "keep an eye on it".

For the mean time, and until I get time to change flush it again, the mobil 1 is still in there. Will keep you all posted! <img src="/forums/images/graemlins/smile.gif" alt="" />

No worries and you've brought up some very good points. Everything has been learned through experience which is obviously far from scientific or even 'conclusive' and if anything nothing more than guesses / conjecture.

The point I'm making is that for me and I guess many on here, if it happens enough times to 'known' individuals, I'll take the safe route rather than be the one to verify it true, especially with a costly transmission. <img src="/forums/images/graemlins/shiner.gif" alt="" />

I read that in my book about using Dexron but I believe the are saying to use that in a pinch and not a full change out. Sorta like saying you can use ATF in your power steering, but power steering fluid is the recommended fluid.

Also, you can search ATF4 Vs Dexron and you will find endless accounts of Dodge Chrysler people having problems when they use anything but ATF+4 (ATF4 is the only other fluid the mitsu techs told me to use when I had to replace my transmission).

I hear ya. Funny thing is the manual does not call for power steering fluid. Next to power steering fluid it says "Dextron II Automatic Transmission Fluid" !!!

<img src="/forums/images/graemlins/zombie.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

We'll get to the bottom of this one of these days!

I have my own feelings on oils and ATF and all ... But one thing know one ever brings up is "foam" ...As in oil putting off or turning into "foam" ... Air in oil is a killer <img src="/forums/images/graemlins/zombie.gif" alt="" />...

Montys do to the gearing and the auto trans work and are made can really get oil to foam .. You guys using Mobil 1 look at the stick and see if theres 'foam' or 'air' drops on the stick ...