Hello all,

Without a long discussion on trans oil I know to you use GL-5 but should it be Dino oil only or can you use synthetic as well. Also, someone mentioned to me that add a GM manual trans additive along with the GL-5. Any thoughts will be appreciated.
Thanks everyone!

Steve

Dino only. Cheapest you can buy will work fine.

Buy it cheap, but change it often is the doctors advice.

Actually, the factory recommends GL-5 .

I use dyno oil, changed every couple of years because I change stuff...

Swepco 201 Multi-Purpose Gear Lube. Ideal for Porsche synchros.

Sherwood

I second the Swepco!

mine came with fresh Swepco in it, changed to dino and it shifts moderately, but noticeably better

YMMV

My local auto parts stores stopped carrying the good GL-5 with no additives in it.. so I went looking for a good alternative.

The single best semi-attainable gear oil I've used in Kendall NS-MP 80-90. It is specifically designed for Hypoid Gears, which 914 boxes use, and it specifically states that it is for non-Limited Slip differentials. Not even recommended for Top-Offs on LSD.

Most of the stuff you find that is GL-5 and Hypoid Gears has LSD additives. The Kendall has none of that. I put it in the gearbox in my dad's car, and he never crunches even the badly worn 2nd gear synchro anymore.

Anyone know what the shelf life is of gear oil? Have a couple containers of gear oil from about 15 years ago. One was opened and half used. The other is still sealed. Wondering it they absorb water or other junk. Haven't done a manual trans in a while but now I have three that will need new oil soon. Should I scrap the oil or use them?

Brett

I use this one, when cold I crunch gears, after a few minutes of driving shifts smoothly .

wnat is API service ?

I use Swepco, not cheap though!

I used Swepco for several years and I never found anything magical about it. The one thing I did like is with the blue colour it was easy to tell the difference between an engine or tranny leak. I still use almost a quart in each change just for the blue colour, that plus the fact I still have a case left over.
Only gear oil that I thought was an improvement was Kendall.

However I do think Swepco 101 grease is one of the best. I get a case every couple of years.

Gear oil fight whoopie

914 Kid has it right. It's hard to find plain old GL5 Hypoid gear oil. I found some CarQuest brand sold by the gallon only. It's super cheap, but it works. You want NON limited slip. Stay away from synthetic and SWEPCO. Makes your trans spin way to fast for old syncros. I tried it in my car and couldn't get it out fast enough.

I never had any problem with Swepco...other than the price.

But then way back in the day I didn't have any problem with Slick 50 either.....

And don't forget that wonderful Swepco odor.

You won't really know until you go back. Probably more than one change to get all the Swepco cleaned out. I need to do another change myself. You have multiple cars, so try the worst shifting box you have. I wanted only the best for my car and so I bought the Swepco. It's hard to believe when you spent all that money it's got to be better. For a new modern trans, yes it is. For an old 914, no.