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2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Heres a great oil video from a muncie Guru. The oil part starts at 14 minutes but the rest of the video is informative also . He has a ton of great videos
My 72 4 speed has always had downshift issues from 3rd to 2nd and 2nd to 1st. since I bought it. I have tried all the adjustments nothing has helped. One of the first things I did was change the gear oil and I used Sta Lube gl-4 85W90 after seeing it recommended here on the forum....Now for the interesting part.....I also have a 99 Toyota 4X4 truck with a 5 speed that recommends using gl-4 it needed changing and I had some left over Sta Lube so I bought another quart and changed it.....Guess what issue I'm having now...Yep downshifting and really notchy shifts till it gets good and warmed up, never had a problem before changing to Sta Lube. I have no idea if that is the problem with either vehicle but I intend to find out. Stay tuned for an update.
My 72 4 speed has always had downshift issues from 3rd to 2nd and 2nd to 1st. since I bought it. I have tried all the adjustments nothing has helped. One of the first things I did was change the gear oil and I used Sta Lube gl-4 85W90 after seeing it recommended here on the forum....Now for the interesting part.....I also have a 99 Toyota 4X4 truck with a 5 speed that recommends using gl-4 it needed changing and I had some left over Sta Lube so I bought another quart and changed it.....Guess what issue I'm having now...Yep downshifting and really notchy shifts till it gets good and warmed up, never had a problem before changing to Sta Lube. I have no idea if that is the problem with either vehicle but I intend to find out. Stay tuned for an update.
Brian
so does it downshify better when going to stalube?
Edit i just ordered a gallon will try it out..i see i used gl-5
And of course i overread all this..and skipped even my own advice from manual stating gl5 seeking improvement..from others but they were older gl4 transmissions.
my 79 needs gl5.. I accidentally posted shell gl5 but corrected my picture to lucas oil gl4 and 5..which is what i had in it..when i got it..
it was low when i bought it and the drain plug was full of hairy metal..couple thousand miles with the lucas ( obviously better than low oil) and plug has zero metal.. i bet never changed since new
i bought and added the stalube gl4 and just got done adding to ...ill drive it and see if i note a difference but will have to get it out of there next oil change or sooner?
I was having trouble shifting into gear from a stop at about 65K miles on the odometer. Changed to Mobil synthetic gear oil and it got worse, some grinding going up in gears and down was near impossible. At 70K I used Pennzoil which worked perfectly. I changed it a 100K and now have 126K. https://www.pennzoil.com/en_us/produ...ion-fluid.html
78 sa with 4 speed, 3:36 rear.
I was having trouble shifting into gear from a stop at about 65K miles on the odometer. Changed to Mobil synthetic gear oil and it got worse, some grinding going up in gears and down was near impossible. At 70K I used Pennzoil which worked perfectly. I changed it a 100K and now have 126K. https://www.pennzoil.com/en_us/produ...ion-fluid.html
what year is yours?
test drive was interesting..didn’t notice shifting any worse..same or better..
but on one high speed 4th gear run it seemed my shifter vibration was significantly less??? Can gear oil effect that?
That's what I use in my 69. It is very smooth with no syncro notchiness anymore. I really like it.
