About to do my Trans/Diff fluids as part of my 30k, and chose to go with the Scotty's Cocktail. My shifter has become more tempermental and noisy in the cold weather and doesnt like going into reverse. So, in the process of trying to get all this crap I have a few questions...

1- I have the Light Shockproof, and am going to get the GM Synchromesh. The Hypoid I found is made by Amalie and is 80w/90. Should I stick with the Penzoil Hypoid C, or will any old Hypoid gear lube work?

2- For the Synchromesh, I am going to go to a GM dealer and buy some today. I however have seen other Synchromesh varieties made by Amsoil and other companies. How do these products differ, and is the GM product still optimal for my application?

3- For the rear-diff. I purchased some Valvoline Synth Power 75w/90 gear oil, IIRC, most anything is ok for the rear diff. as it is a closed unit. ya?

4- Is there anywhere that sells most of these products online? Now that I am working so much, it is hard for me to get out and get some of this stuff, especially when I only have sundays off.

5- When putting it all in, should I purchase a new/clean funnel? I can just fill it all at the trans dipstick and it will mix properly on its own?


Thanks to all, I have heard nothing but good things about the cocktail so far.

Never tried that but 2 parts Light Weight Shockproof, 2 parts MT-90 works wonders. You won't get any syncro grinding with it and can shift into 1st at 20mph with a light rev.

Scotty says the Castrol HypoyC is as important as the Synchromesh or Redline Lightweight Shockproof.

For the Synchromesh, you can use Pennzoil Synchromesh found at Autozone. The original cocktail called for 75w90 HypoyC, but that is probably discontinued and Scotty says use 80w90.

I "broke" the recipie by using 75w90 Valvoline dino oil instead of the HypoyC, the shifting is still in that "magical zone" that you feel right after you change, so only time will tell...

For the rear diff, any synthetic 75w90 should be hunky dory.

So go for the regular Hypoid-C as opposed to the other hypoid gear oil? I dont really need to shift to first while rolling, but when cold my car doesnt want to shift into second when rolling faster than 15-20. Once warm it shifts fine, but lately it has been taking a while and has been a little noisy

Guess I will go to autozone later and the GM dealer...bump for more info

bumpity bump