While changing the starter in my girlfriends 97 shortbox, i decided to check the tranny fluid and it was down. I looked in my book and it said that tranny, the 4500, takes Castrol Syntorq oil. It didnt list a grade or anything else. I also checked a GM service manual at work and it said the same thing. What is syntorq oil?

I went to the dealer and bought the right stuff there for my '92. Sorry I can't be anymore help. BTW, it is nice to see another person from Ontario on here.

On another website, there was a discussion for the use of Castrol Syntorq oil in the NV4500 gear box and the feeling is that the Amsoil severe gear 75-90 will out perform the Castro oil. Keep in mind that Amsoil is a quality oil and is good at removing heat from a friction based gear set. I run it in my posi-track rear ends for a friction reducer. At no time is either lube a cheap investment, but a little GOGGLING might produce a better shifting tranny.

I had a rock hauling truck from International that had a hard shifting manual tranny many years ago and the manufacturer recommended "Mineral oil" from the local pharmacy to help it shift better. It is amazing what simple oil compositions can do.

:tj: Sorry to thread jack, the tranny in my truck grinds "a little" when downshifting and sometimes slightly when upshifting, I am running the proper ACDELCO fluid with half a bottle of Lucas in it and it still does it. Any ideas other than a rebuild?

Has anyone considered trying some "Energy Release" in their trannys? I am running this so called "Snake Oil Additive" and I believe that it works quite well. One should Goggle this stuff and see what the experiences of using it is. I have it in my engines, automatic trannys, rear ends, and power steering pumps. I had a motor crankshaft fail at a 140,000 miles on it. There was flaw in the casting just behind the timing chain gear, so it broke there. The bearings, timing gears and cylinder walls showed relatively little wear compared to other engines with that amount of miles.

This stuff infiltrates the pours of metals and creates a low friction barrier that helps to lessen heat and dragging issues. A tranny that is shifting hard, or maybe grinding a little could be helped tremendously by this stuff. It is marketed through the "O Reilly's" auto parts store chain for one source. There are manufacturing companies in my area that uses this to make their cutting tools last longer. There is a group of us that buy the 5 gallon container and then split the product out in smaller containers. This saves us a large amount of money. If the tranny doesn't get better by using something like this, then it could be in need of new synchros or bearings.