5 speed tansmission oil GM 12345349
#16
Rennlist Member
Soooo, what have we learned here??? Dexron III is good for our 5-spds? At least mine? (Hehe)...If so, sweet for me...I got a whole case of the stuff in me storage shed....I was going to get rid of it, but now....or should I go 75w90?
#17
Nordschleife Master
I'd also choose based on your diff - if LSD I'd go with a 75W90 that has the correct additives for LSD. If open diff, I'd have no problem using Dex III per the WSM.
If you're not sure which you have, you can tell by having a look through the fill plug using a cheap ebay endoscope, or just take snaps with a digital camera in macro mode.
Take pics/look at 90-degree positions around the diff (i.e. rotate the rear wheels) - the massive holes and gears visible in the open diff cage are easy to spot.
#18
Three Wheelin'
Ron,
after reading about fluids today more than anyone should have or want to I have two things to say: 1) make sure the DIII is the old type (thicker), and 2) I will be using Redline 75w90NS and adding the friction modifier 1oz at a time until my LSD no longer chatters.
after reading about fluids today more than anyone should have or want to I have two things to say: 1) make sure the DIII is the old type (thicker), and 2) I will be using Redline 75w90NS and adding the friction modifier 1oz at a time until my LSD no longer chatters.
#19
Administrator - "Tyson"
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#20
Drifting
See how your car shifts first,
i added it to mine only because i have slightly hard downshifts 4th to 3rd and 3rd to 2nd, otherwise i wouldn't use it because it's pretty thin.
It helped a great deal. I am still surprised how much it helped. Warm up time is much shorter. I only did half Dexron & 1/2 cheapo conventional 75/90 from Walmart as a test.
#21
#22
Drifting
But when you have tiring hard shifts and are faced with a rebuild anyway, why not give the DEXRON a go? There's nothing to lose.
Also Dexron was used in the rear axles of big American cars protecting them from wear just fine.
#25
Three Wheelin'
I just looked at some syncromesh I have and noticed it's thin. It's thinner than any other type of oil in my shop except WD40.
I bet it does improve shifting though!
I bet it does improve shifting though!
#26
Three Wheelin'
There's no "equivalant" to that Dexron today.
#27
Three Wheelin'
Owner's Manual for 78 and 79 states Dexron can be substituted in the 5 spd when 75W90 is not available. Dexron III (which is what was around in 78 & 79) is no longer being produced. Dexron IV is backward compatible in automatic transmissions but not in manual transmissions or transfer cases that called for Dexron III.
Again, there is no equivalant to real Dexron available today and hasn't been since the 70s.
#28
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Right, looks like Dexron II is what was around when the 928 was introduced, and that came out in 72 after they banned the use of whale oil in the original Dexron.
#29
Three Wheelin'
They really should have stopped using the Dexron name completely after the ban, anything else is basically just bulk hydraulic oil with friction modifiers.
Just thinking out loud here but I contend that if Dexron (or any other whale oil lubes) weren't around in the 60s, limited slip diffs would have been designed differently to prevent complaints of creaking.
#30
Administrator - "Tyson"
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With the early cars it's clear to me mis-adjustment of the double disc clutch combined with the Porsche style synchros is recipe for bad shifting.
You know as well as anyone around here, do a search and you will find thread after thread on the "horrible" notchy transmissions in the 16V cars, 2nd gear is difficult, they grind etc... along with endless chemical solutions to "fix" the problem.
Meanwhile I have over 100,000 miles on the original transmission in my 81 with over 400rwhp and it's smooth as silk. I'm also one of the most **** retentive owners when it comes to clutch adjustment (had it out 20 times i one day trying to source a slight hang up issue).
You know what they say about leading a horse to water.........