1985 308 QV trans fluid replacement

I'm sure it's been covered many times before, but I don't seem to be able to find anything. My question; when draining and replacing the transmission fluid on my 1985 308 QV, can I refill it completely with Redline 75W90 synthetic, or do I need to concoct some sort of blend of mineral/synthetic oil? Obviously, I have the dreaded "no shift into second gear when cold" syndrome. RSVP.

 

I just changed my gear oil a week ago with Redline 75/90 NS. It's pretty straight forward, just drain it from the transfer case and from the gearbox for as long as 1 hour,
replace copper washers if you can then fill it from here but your going to need 12mm allen wrench for this. I use a total of 5qts. And yes it does help the cold 2nd gear shifting.
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Rusty suspension arm. It't time to clean that sucker up.

 

Be sure to use Redline 75w90NS MUST BE NS !!! (not just 75w90) no concoction required. Some have needed just a touch of slip additive but I didn't and I have an 85'qv as well. You'll love the difference.

 

exactly

 

I know my shop did use Red Line but I think put in non-NS (last July '07). We did not know there's a difference. My '83 QV trans has been impossible going into 2nd for the first 10-15 min, then it's fine. Is there an additive I can pour in till the next fluid change that may help this 1-2 shift or should I just replace it now and see if it helps?

 

I think you have to replace it. The non-NS has too much slip additive. NS means no slip additive added, you have to add some ONLY if you need a little. (too much is the problem)

 

I see, thanks. But it seems counter intuitive. I would think you want MORE slip in the fluid to ease the shifting, no?

 

The limited slip diff and the syncros need a particular coefficient of friction to operate as designed, too slippery and the syncros won't "brake" the rotation of the gear/sliders and allow smooth engagement.

FYI, I am using Redline MT90 rather than the NS, on advice of A. E. Haas (lubricant guru), and it works wonderfully. Absolutley no shifting issues, even hot on the track. Before switching, I did have that cold 2nd gear thing, gone now.

see here http://www.redlineoil.com/products_gearlubricants.asp?productID=46&subCategoryID=17&categoryID=7

 

No. The synchronizers make the shifting easier, not the slip modifiers in the oil. For synchros to do their job, they need a certain amount of friction so that they spin up the gears so they mesh when you go to shift. Too much slip additive and the synchronizers can't do their job and the tranmission can get balky. Definitely use Red Line 75W90NS. I've used it in my 308 and previously in my Mondial QV, and it works perfectly. I have not needed any slip additive for the differential at all.

BTW, the 75W90 hypoid gear oil for the differential is designed to keep the rings in the differential from hanging up in hard turns. That's where you need the slip additive. Our boxes are more transmission than differential. You only need to add some slip modifier if you hear groaning in the rear end in tight corners. Most of us who use either 75W90NS or MT-90 have had no problem with groaning differentials, even on the track.

 

Thanks to you both for this info.

So, considering I drive the car mainly on the weekend about 50-150 mile and do not track it, which do I go with then? The NS or the MT ????

 

I'm not sure what type I have in the trans but when the guy did my ppi he said it had the wrong fluid in it and it should have been blue and it wasn't so the owner changed it to make the sale and the shifting was 100% better and it cost him $80 a gal I was told! the guy that did the ppi said if change the fluid didn't help the shift then it ment a trans rebuild and if it grinds it diffently does need one,oh,its a 85qv

 

I changed to Readline MT-90, from Quaker State that I got from the local dealer. Huge difference! Like a new gearbox.

 

I had the same decision / dilemna as you. My research ( Ali Haas, and other threads here) led me to decide on the MT-90, due to the limited slip diff being part of the transaxle etc. I will continue to use the MT-90, It works.

My .02

 

Why Red Line? Any issues with using Royal Purple gear oil? What is the capacity? 5 Quarts?