GMC Update

As some of you may know, about....a year ago, perhaps a few months more, the truck started to "act up." Mainly in the form of an occasional rattling sound underneath, usually after it was started and idling, and having to give it a little throttle when in reverse so it would back up.


Well, over the course of a year, the rattling sound never really changed, except the transmission itself got much worse overall. When cold, it wouldn't shift into 3rd right away, I'd get up to 24 MPH, and it would downshift into 1st once, then catch and go into 3rd, reverse never worked until it was warmed up, and it would shift in and out of OD from 45+ MPH, and the entire truck would rattle horribly while it did it. In addition to that, whenever you tried to back down a incline, the truck would jerk and bump like it was it was trying to go into Park or something.

I hated driving it like this, but, seeing how I don't have the money for another transmission, I adopted the idea of just drive it gently, until it won't move anymore, then go from there.


Well, between February and yesterday, my nice pink fluid has gone from pink and clean, to a red/grey with metallic particles in it. That's....a sure sign she's got one foot in the grave and another on a banana peel. I drove it up to the shop, and was talking to Billy up there about it, and over the next 45 minutes or so, amidst conversation, he mentioned Lucas Trans Fix. Now, I've never used any of those "magic in a bottle " kits before, and told him that I'd always thought those products either didn't work, or worked just long enough for the poor sap to buy it off you to test drive it, but he told me he uses it in all of his vehicles, especially his racing cars. I knew it was a friction modifier, and we got to talking about it, so I decided to go on ahead and buy a bottle. Worst case scenario, it did nothing, and the trans would die.


Put it in, and went for a drive. About 10 minutes, I guess.


Folks, I'm not one to say one thing was a miracle over another, but it drives like it did the day I bought it. If it didn't make that rattling sound underneath, I would have had no idea anything was ever wrong. It shifts almost as good as my car. The only time I feel it shift is when it goes into OD, and even then, it's hard to tell. No more vibrating, slipping, missing or hard shifts. I just really wish I had done this a year ago, and the transmission would be in a lot better shape internally than it is now.

The guys I know at the shop were looking it over with me one day, and they said it has (had) the symptoms of a failing trans. pump, but only time will tell, I suppose.

I plan on driving it like it is for a few months, and if it still drives like it does now, I'll drop the pan and change the filter and fluid, and add another quart of the stuff. I still can't believe the difference it's made. I may just fix the A/C now.

me and billy think alike.. im the same way and i use it in everything as well.. seems that stuff has built a name for itself as a miracle cure.. lol. happy to hear all is well.. stop back around sometime.

It does work. Fixed the trans in my 85' too. Its good stuff.

I've never been a fan of an kind of additives.
But for the past year I've been trying stuff and I've only heard nothing but good stuff about Lucas additives.
I'll have to give it a try.

In2Trux wrote:

I've never been a fan of an kind of additives.
But for the past year I've been trying stuff and I've only heard nothing but good stuff about Lucas additives.
I'll have to give it a try.

I was/still am in the same boat. However, I'm a believer with this stuff.


I checked the fluid today, and while it would appear I need to add some (the dipstick was dry except the very end of the tip after I wiped it off and re-inserted it when it was parked and idling) I no longer see any metal particles in it. It will still be changed, nonetheless.



Two questions, I suppose.


The fluid is supposed to be checked, after the engine is at operating temperature, with the truck in Park, and on a level surface, correct? I've never gotten the same level twice, and I don't see it leaking any under the truck anywhere, so I don't know if I'm safe adding some or not.


How much fluid should come out of the transmission when I drop the pan? i.e, how much should I add? Normally I wouldn't ask that, but since I never seem to be able to check it at the same level twice, I don't want to overfill it. Unlike my car, the truck doesn't have a bolt in the TC so I can drain the fluid out of that, so I can't go off the total in the owners manual like I can with the car.

Sorry Sierra
It's been a month since your post..
I know exactly what you mean on the dip stick check and continually getting a different reading.

You would think with all the technology out there, they would come out with a more accurate way to check your fluid levels.

I check my tranni and couple of times in a 10 min period and just use the average.
Not sure if this is good (correct me if I'm wrong) I will check my tranni in the morning before I move the truck. I start the truck after I've checked the motor oil... shift to D and then to R then back to park without moving the truck at all. get out and check the fluid. This way, very little fluid has gotten up the dip stick tube to contaminate my dip stick reading.

Hey Glenn,

Transmission fluid should be checked when the vehicle is packed on a lever surface, fully warmed up, and idling in Park.

1993GMCSierra wrote:

Hey Glenn,

Transmission fluid should be checked when the vehicle is packed on a lever surface, fully warmed up, and idling in Park.

Ya I realized all that, but figured seeing as tranni fluid maintains the same volume whether it's worm or cold. I thought a person could get a more actuate dip stick reading if they took the reading in the morning before moving the vehicle. Idling and in Park

as long as its flowing. and lucas is good. at least i know the oil additive is. stops leaks great.