Tremec Hi Performance Transfluid in T56

[RetroJonez]

Hey All,

So finally have the car running great (1998 GTS) had a bunch of problems if anyone remembers. Last summer I replace the transmission fluid with Tremex HP MTF. Looked good for the T56. https://www.tremec-store.com/collect...smission-fluid

Then last weekend I started noticing some rattling marble sounds at idle, barely touch the gas, goes away. Goes away slightly with clutch depressed. I am assuming this is the common neutral gear rattle.

That said, I never had it prior, and I came across this press release from tremec. https://www.tremec.com/not_am_detall...mission-fluid/

"1-quart bottles of HP-MTF indicate that the product is recommend for assemblies manufactured from 2008-to-present. This is due to crossover considerations related to various OEM programs for which we cannot guarantee compatibility—namely the “carbon paper” friction rings commonly found in early T-56 transmissions. TREMEC has NOT validated the compatibility of HP-MTF with this material."

Im not sure why it says carbon paper rings. I thought it was either carbon or paper, should I drain it and replace it? Dodge dealership said their fill is now Mopar ATF+4. I don't want to start the heated transmission fluid debate, but assuming I should get this fluid out of there? Then ATF+4 sound good? or is something else now the go to?

[RetroJonez]

Also, for what it's worth. I have a fill with Castrol Syntech sticker on my transmission. The thing I can't find a definitive answer on is whether the transmissions with the castrol synth sticker were all carbon blockers. It seems like they swapped to synthetic to mitigate neutral gear noise, but then later recommended atf+4 when it was learned it wasn't good for the paper blockers. I am wondering if maybe in 98/99 they just switch to synth even if it was paper blockers, because of the TSB.

For what it's worth, Amsoil (which I know can be controversial) recommends ATF through 99, and then 2000+ MTF.

I read this on another thread which adds to the confusion.

"Synthetic **** (Mobil 1, RedLine, Royal Purple) should NOT be used on pre-2000 T56 transmissions as it can eradicate the paper blocking rings in them.
Post-2000 T56 transmissions have Kevlar blocking rings, so synthetic **** is okay."

But it looks like some 98's including mine had synthetic from the factory.

[Steve-Indy]

No debate necessary. You are experiencing the well known NGR (Neutral Gear Rattle) that Viper T-56 transmissions had/have running the OEM factory fill which started off as Dexron IIe, then Dexron III...both of which are ATF's. Due to customer complaints about the NGR, Dodge switched to Castrol Syntorque 75W-85 (i.e. relabeled as MOPAR Synthetic Manual Transmission Lubricant 75W-85) for 1999 (some late 98's ??)and as a TSB (Technical Service Bulletin) allowing a free one time fill for the complaining customers with this thicker gear lube.. This remained as the factory fill through 2006. It is a GL-4 which is safe for the T-56. Some older Corvettes also used this product...and, some folks are still finding it at GM stores though that source seems to be drying up now.

For my next round of tranny fluid changes for our 95, 96, 97, 99, 01, and 03, I will use MOPAR ATF+4...and enjoy easier cold shifts while accepting a little NGR...AND, not having to worry about the gear lube getting hard (with time and heat) causing some "gumming up" issues as reported by a few experienced techs.

[RetroJonez]

Oops I accidentally deleted my post. So since I have the synthetic sticker on the transmission though it sounds like I had synthetic as my default fill. I only get ngr when it's warm and I have synthetic in it now. The rattle doesn't really bother me I was more concerned if I have the paper blockers then I would want to get ATF in there.

Either way I have Mopar ATF+4 in the garage so I could swap it out anyway and give that a try

[Steve-Indy]

RetroJonez, we are all in the same boat...as the manufacturers have "moved on" and, in my opinion, they don't care to spend the time and money necessary to give us the factual answers that most uf us want. Furthermore, in some cases I am NOT SURE that they had (let alone kept) all of the data from all suppliers in the first place.

As has been pointed out before (at least behind the scenes) Stellantis is in the business of manufacturing and selling NEW cars.

Final point: if you have NGR using the TREMAC HP-MTF, I would expect you to have NGR using ATF+4. Maybe others who have used both can provide better real-world info.

[RetroJonez]

Well I got under the car today. I assume I would be able to hear NGR from under the car too? I can hear rattling in the car coming from where it sounds like the bellhousing would be, but when I get under the car I don't here much. But it almost sounds like its coming from the crank case, which isn't great. Ill drain the oild and see if I see anything. If not I might drop the oil pan.

[RetroJonez]

Well, I dropped the oil pan to be safe. Nothing out sorts there. I do have an aftermarket cam, so it must just be noisy. And when I got the old fluid out last year and put in new stuff it introduced NGR.

[RetroJonez]

Upon further inspection I found one metal shaving the in oil pan. When I had the car running the noise was equally as loud with the clutch pedal depressed or engaged. I could really hear the noise from the engine bay toward the rear. Is there a rear bearing that could have bit the dust?

[Steve-Indy]

Damn...Sorry to hear that !!

[RetroJonez]

Yeah not great. Although, I'm not sure if it would be a bearing, it looks like it was the only issue in the oil. Granted there should be no metal/aluminum in it. I will cut open the filter. But, its for sure not a knock, so I am not sure what could be make that sound. It for sure sounds like marbles or a box of rocks. Definitely not a knock. Goes away when the gas is barely touched. Assuming if it was the transmission it would stop when I disengage the clutch. I will have to get more things apart. At this point I don't think the tiny shard is related to the noise, even though it is also concerning. Maybe an input shaft bearing. Really bad pinging. Interested to see if anything is in the oil filter.

[RetroJonez]

Worst case spun bearing piston slap. Also, since i have had the car, the oil pressure gauge has always read 60psi, doesn't really ever move. So I will try to swap out the sending unit. Would be nice to know what my pressure is.

[daveg]

Final point: if you have NGR using the TREMAC HP-MTF, I would expect you to have NGR using ATF+4. Maybe others who have used both can provide better real-world info.

Steve, to answer your question.. My 96 GTS with ATF +4 in it had NGR. With the TREMAC HP-MTF, it disappeared. I have read 2 conflicting articles on using the TREMAC HP-MTF fluid in a T56, One said it was safe, the other said they did not test it.. So who knows..

[Steve-Indy]

Thanks, Dave. Sounds like it is the motor from his reports. I hope it is nothing too big.

[daveg]

Thanks, Dave. Sounds like it is the motor from his reports. I hope it is nothing too big.

Ya it sounds like it, I just wanted to chime in with my results incase someone runs into this thread and was curious about the TREMAC fluid.

[RetroJonez]

Thanks, Steve, for sending the Delco part number. Ordered some of that. In the meantime I put some redline mt-85 synth in just to get it on the ground again. Started it up and everything is purring. The rocks/marbles don't come till it's warm and after being driven. I haven't had the chance to take it back out yet to see if it's resolved.

But I assume, maybe incorrectly, that if it was something really major like a spun bearing it wouldn't be so intermittent. Also I probably have 250 miles on it since I first noticed it and it didn't get better or worse. Also had some pretty hard drives in those 250 miles.

I was poking around with a stethoscope when it was warmed up today and nothing sounded out of the ordinary.

When I had the oil pan dropped nothing look out of the ordinary in the crank case either.

Still haven't cut open the filter.

Also, because I'm and idiot and wasn't paying attention, I f'd up one of the intake tubes on the k and n intake because I started it with them disconnected to sync the throttle bodies and the alternator rubbed a hole in it, so might need to exhaust tape that as a stop gap.

[RetroJonez]

Just wanted to bump this as an update. Replaced the transmission fluid, the sound is still there, albeit not as loud. In neutral, whether I have the clutch depress or not still the same sound. However, I have noticed, if I am pulling the car into the garage and am only enging the clutch to ease it in, and not on the throttle at all, the noise gets pretty loud, so I am assuming it's neutral gear rattle that really starts clunking when under a bit of load at low rpms in first. There wasn't any shavings or anything in the oil filter.

[RetroJonez]

But I guess I have to ask technically if I'm getting that rattle at low RP m's in 1st gear pull in the car into the garage technically I'm not in neutral gear. Would that be indicative of another issue?

[daveg]

Replaced the transmission fluid

What did you replace it with? With the car in gear AND the clutch depressed, you shouldn't have NGR.

[GTS Dean]

True this, unless he has a broken clutch spring rattling around inside the pressure plate.

[daveg]

True this, unless he has a broken clutch spring rattling around inside the pressure plate.

^^^^^

[RetroJonez]

The AC delco MTF (10-4119) that sounded like it was the castrol equivalent. I can get a video of the sound tonight. The sound is most notable when the clutch is engaged and I am easing it into the garage. When I'm sitting in neutral, the sound is faint and doesn't change regardless of clutch status.

[RetroJonez]

True this, unless he has a broken clutch spring rattling around inside the pressure plate.

This was actually something I was wondering about. Did something break in the clutch. Only one way to find out. I was going to put in a light weight flywheel and new clutch this winter. So I can get a jump start on that.

[RetroJonez]

Around the 35 second mark. It starts the rattle as I ease into first. As the car warms up it's also louder, but doesn't seem to matter if I am on the clutch or not. It does go away with even the slightest rev.

[dave6666]

I didn't hear a thing that doesn't sound normal. But then of course I'm listening to a recording with a tiny laptop speaker.

[RetroJonez]

Yeah, I also recorded it with a phone. I might try to find a different way to grab it. I might try to get my stethoscope on it and have someone else engage the clutch and hopefully not run me over.