NAPA Transmissin Fluid.

Hi,
Any one ever use NAPA Premium Tractor hydraulic & transmission fluid in a Thiokol O/C rear end?
Denny Todd

I think you will find that stuff to be too thin. It is basicly 10 WT oil.

I use Caterpiller fluid. I forget the weight. I have a post. The stuff works perfectly! I will look for the thread.

OK here is the thread I was talking about:
Well today I decided to change my OC12 diff fluid out again. Thought I would walk you through the process. This is real easy stuff and really helps keep those OC12s in top shape. This is the second time since I bought the cat last year. After talking with SNOWCAT PAT who is probably the only OC12 expert out there. He suggested I use Caterpillar TO-4 30 weight fluid. OK heres the pics and also pictures of the tools you will need.
__________________

Scroll down toward the bottom.

http://www.forumsforums.com/3_9/showthread.php?t=10193&page=11&highlight=diff+fluid

Just sharing my experience trying to locate the proper fluid for my OC-12. I bought a 1986 LMC 1200 last year. The dealer was to have changed all the fluids. He told me that the rear end took a 90W rear end fluid. One I got a manual from Peterson's, I was able to go back and check things to make sure they were done properly. The manual called for fluids that were not available today. I also looked at suggestions in the forum. When I checked the rear end fluid it was dangerously low, so I headed for the NAPA dealer in Leavenworth WA. We are near Steven's Pass in Washington State. The unit I have also has a hydraulic blade that apparently uses the OC-12 as it's reservoir. From this forum I was able to glean types of fluids and specs. for them, but when presented to the NAPA dealer I got a big HUH!? They were very helpful but did not the cross references necessary to figure out what they had that would fill the bill. I had to make a decision by reading the the labels on the 5 gallon pails and looking for manufacturers specs that it said it met. I settled on NAPA Hydraulic / Wet Brake Fluid (# 85-405) They could not tell me the viscosity, but I figured anything would be better than nothing. I got two five gallon pails. It took one of the pails to bring the level up to the fill hole. I later found out that there is approximately seven gallons in my system. There were no leaks in the system so I figured they may have overlooked the rear end oil service. Things worked well and I found out that this is a 20W viscosity.
We use the cat for access to a cabin and puttering around the area. The rear end had a temperature guage and rarely comes off the bottom. If we go out and explore the guage will come off the bottom but never to a dangerous temperature. For our use it seems to work just fine.
This summer we had a mechanic / service person that covers the Northwest area for Peterson's come in to do a once over check on some of the Thiokols in the area. They did a once over on mine and replaced some minor maintenace items. I asked about the NAPA fluid I chose and they said that it was fine to use for my application.
I do not know your vehicle components or usage, but now you have my experiences to put in your knowledge bank. I know it can be frustrating when you find out there is something seriously wrong and you do not know the proper way to remedy it. I was not this calm when it happened. Hope it helps!

I went out to the barn this morning to get the empty bucket to make sure I gave you the right specs. The viscosity is 10W-20 not 20W. It shows that it meets or exceeds Caterpillar
TO-2. The name on the bucket is PREMIUM HEAVY DUTY TRACTOR HYDRAULIC & TRANSMISSION FLUID.

http://www.napaonline.com/MasterPag...ription=Hydraulic+Fluid+-+All-Purpose+Tractor

We also have two very knowledgeable memebrs here who would know exaclty what we need for what ever application. Snowcat Pat and Boggie. They both work with OC12s. My new cat has a blade so I too do not know what to use for the hydraulic application. (except whats stated above now) Also I have found Petersons to be very helpful when questions are asked. I am very satisfied with the cat To-4 so far. Buyt thats for a non hydraulic application.

Any news

If I got a penny for every time I've had this discussion....

We use TO-2 rated oil for OC-12's that have the rear end oil and diff case as the auxilliary hydraulic system reservoir. Specifically we use Shell Donax TD universal tractor hydraulic fluid. There will be hoses connected to the bottom of the rear end case and aux hydraulic control handles in the cab for the blade and rear implement...

We use TO-4 rated oil for OC-12's that Do Not have the above, that is, the rear end oil is independent of the aux hyd system. Specifically we use Shell Donax TC-30. There may or may not be an aux control handle in the cab. There are not hoses on the bottom of the case, but there may be a bumped-out lid with hoes connected from the aux hyd system. The reason we use this oil for the non-integral-aux-hydraulic applications is for better gear protection than the TO-2 because of the heavier weight, and since there is no real cooling system for these OC-12's There is also TC-10, TC-40 and TC-50. I use TC-40 in the OC-4. I notice better steering performance with the TO-4 oil.

Both the TO-2 and TO-4 rated oils have an additive package for gears and wet brakes. They are approved for Allison Automatic trans's. I'm no petrol chemist but it is interesting to read about the development of these oils that fit our applications perfectly. The ring and pinion in these diffs is a spiral bevel and does not require hypoid lubricants (GL-5) which of course will ruin the brake linings.

There are exceptions to the plumbing arrangements I mentioned so you should do some checking to make sure of your own situation. If still in doubt the fail safe for OC-12 is the Universal Tractor Hydraulic Fluid (TO-2)

I just wish I could explain it better.

-Pat

The under filling that Silvia mentioned is a very common error mechanics can make. It does indeed take 7 gallons for the Drop-Box equipped OC-12 but whats not so obvious is that it take moving the machine a little to get the level to settle. The oil takes a while to completely fill (yes, completely) the axle tubes and drop box cases. Strange but true.
-Pat

I think you are short changing yourself, that information is worth much more than a penny!! Thanks for taking the time to do it again for us "newbies".