I've tried a lot of different things over the years and have never been completely satisfied with anything in particular. Royal Purple gives me the quickest shifts but I like the 'feel' of petroleum Valvoline.
I'm in the process of breaking in/flushing out a rebuilt trans and am thinking about what I'm going to put in it after I change it.. Wondering what everyone else runs. Hope this thread doesn't get too out of hand.

 

25/75
75% fluid of choice gear oil
25% automatic transmission fluid

 

Smart, I've tried striaght ATF and 50/50 and both work well.

 

Royal Purple

 

how this oil

 

I've thought about this, but I currently have 75W90 synthetic in my trans and diff.
Lot's of racers use the 75/25 or 50/50 90W/ATF. They swear by it for longer trans life under racing conditions.
Might try it in my SE. It's gonna see more track duty than street duty.

 

I'm not sure, it probably does. IMHO, the easier the shifts are the longer it's going to last. Royal Purple is nearly clutchless honestly. But I really do prefer the valvoline. Probably will go with the semi-syn.

 

I've run the 50/50 mix for a couple of decades in a number of vehicles. I swear by it, always makes an improvement every time.

So now, I'm just trying different oils to go along with the ATF. Last change, I used Lucas gear oil along with Lucas ATF. I did this simply because I have a lot of respect for their products. I've even used their motor oil since Autozone began carrying it, and I love it (less smoke, great lubrication according to noise level of engine).

In fact, the tranny that blew last year was a used/unkown mileage unit that I had put in a couple years ago. I only installed it because my original tranny was at 213,000 miles and had a slight "scratch" when shifting into 2nd gear quickly. So when the "new" tranny failed, I put the old one back in. When I did this, I used the Lucas products rather than the usual 50/50 mix. Remember that problem with 2nd gear I mentioned? Gone! And that tranny never shifted so smoothly or quickly before, even with the old mixture. I like Lucas products a lot (did I mention that?).




.

 

I might try this in my Nissan pickup. After 241K, it's getting a bit difficult to get into 1st or 2nd. Time for gear oil change anyways, and the recommended 75W is rather scarce around here.....

 

I'm running a mix. Was 50/50, but some got drained out and replaced with regular gear oil, so it's probably closer to 70/30 now. Works great.

 

But when running a 50/50 mix what ATF type do u use and what weight gear oil?

 

80/90 with Regular dextron 3
75/90 synthetic with ATF+4 synthetic tranny fluid
It would make sence to put synthetic with synthetic and not mix them but its your choice for whatever you want to to

Lucas 80/90 with ATF 3 50%
Lucas 75/90 with ATF+4 50%

Lucas 80/90 with ATF 3 25%
Lucas 75/90 with ATF+4 75%

Valvoline 80/90 with ATF 3 50%
Valvoline 75/90 with ATF+4 50%

Valvoline 80/90 with ATF 3 25%
Valvoline 75/90 with ATF+4 75%


The Combo list continues and im not going to do it all, i hope you can figure out the trend

Its whatever you like i for fluid mixed with different fluids. i change my tranny fluid once a year! so you can mix and match and just see what feels the best.

 

Tossing Redline Syncromesh in mine, seems like a good idea to me at least...

 

Redline 75W90NS. After you start breaking these feeble fragile transmissions every 6 months you won't waste your time with anything else.

Guys ATF works great for cleaning out the tranny, but it simply does not have the shock loading properties that real gear oil has. It is also just too slippery for the syncros to work properly. You cannot run it for long and expect a tranny to last on anything making over 140lb/ft.

 

I dunno. Mine's holding up just fine so far, and I'm sure I'm making well over 140 ft-lbs. And my synchros work way better since I switched to 50/50 (this tranny was seriously ready to be junked before, it was that bad; the 50/50 mix was a last-ditch effort to keep it going until I could swap in a better one, and that was more than three years ago now). Granted, I don't drag race, but I do abuse it on a regular basis. I also have one of the best-feeling shifters of any FB tranny I've ever used.

It's working fantastically for me, so I'll keep using it.

 

Well you didnt read the fact that kentetsu had run his car to well past 213000 miles with a 50/50.
Or that a bunch of other people who use there cars for racing had said the same thing.

 

Maybe you need stop buying used and high mileage transmissions and learn how to shift (match the engine RPM)

 

I was offered a gray bucket of prototype gear oil in 84. GM was burning up the rear ends in the '84 Camaro/Firebird in SCCA classes. Mobil came out with Mobil 1.
I've used their synthetic products and have never had a lubrication failure since 1984 in Mazdas. Used to use Valvoline Racing 20w-50.
Nevver had the desire to use DEXRON, (not DEXTRON), in anything but a THM trans. GM spec'd this in their manual trans for a while but then went to snythetic motor oil instead.

Mobil 1 for me because it saves me money and down time.

GD

 

yes your right DEXRON! my bad its been a while sence i had to spell it i went from automotive work to being a war fighter for uncle sam so forgive me for forgetting how fluids are spelled.
You are 100% correct synthetic is the best way to go in any lubrication fluid.

 

Does it matter if the tranny fluid has the limited slip additive? Royal Purple 75-90 Max Gear has the LS additive and I was planning to use both in the rear end and tranny of my GSL-SE

Thanks Steve

 

You only need the addative if you have a LSD, and then only in the rear end, not in the tranny.

 

IT CALLS FOR GEAR OIL.


NOT ATF.

 

The manual calls for 80-90 weight gear oil in both the rear end and the tranny. Can I use gear oil with the LS additive in the tranny?

 

i may be wrong but i think most synthetic gear oil has the LSD additive in it??
I use to work at a oil change an i think the bulk stuff we had already had the additive in it.
Maybe it was just a certian brand.

I wouldnt not put it in the transmission, ATF is one thing but a additive that makes things grip better i wouldnt want that in my tranny.

 

Been using Redline for about a year, so far I like it.