Gear lube vs SAE 30wt for Final Drive

[psmith]

I need some help selecting an oil for a Komatsu PC40-7 final drive. Judging from the pictures in the manual its a typical planetary reduction gear set in the final drive. The manual calls for a SAE 30wt CD oil. I believe this is a straight weight diesel oil. I currently put in a Rotella SAE 30wt CJ oil but what I drained out was defnitely gear lube that needed to be changed.

Going by the viscosity charts on here both a SAE 30wt and an 80wt gear lube are about the same. My question is which oil is better for anti wear on the internals? Cost of the oil is not an issue but I do want something easy to get locally, ie. no amsoil stuff.

 

[JHZR2]

Why not use something like the Amsoil 5w30 MTF? Though you say locally available, Im sure UPS delivers to you.

Id think that gear oil would be better, but you need to be sure of the add packs and yellow metal compatibility.

 

[psmith]

I don't think there is any yellow metal in there but I am not sure. Wouldn't the 5-30 be a 5w base oil to which VI improvers are added to make it a 30 weight at temperature?

 

[JHZR2]

could be, but syn oils with high VI can be blended such that they require minimal, if any VIIs.

 

[MolaKule]

Or go Hog Wild and install the

http://www.amsoil.com/storefront/acd.aspx

or

http://www.redlineoil.com/product.aspx?pid=140&pcid=7

 

[Rob_Roy]

When in doubt, follow the manual. The SAE 30 Rotella you selected is fine.

 

[psmith]

I agree with following the manual when in doubt. Its just that its 15 years old and I feel that lubricant technology has come a long way. Just looking for an oil with the best add pack for this application. Does anyone know the anti wear and EP add packs of 30wt engine oil vs a GL4 or 5 gear lube? It would seem to be the pressure and shock loading in the final drives would be similar to a differential vs an engine. Is the difference between GL4 and GL5 oils the lack of sulphur in the gl4 oils that make them safe for brass parts?

 

[Rob_Roy]

GL4 gear lubes were available 15 years ago, and yet that is not what the OEM specified for that application. I can't say if running a GL4/5 gear lube would harm anything in that compartment, but I don't think you'd gain anything either.

I think an upgrade from plain engine oil would be an approved SAE 30 Caterpillar TO-4 fluid. Many products that are TO-4 approved also meet Komatsu's current specs.

You can get one from your local oil jobber, AMSOIL, Schaeffer's, Texas Refinery, etc.

The swing drive may also call for the same fluid...check and see if that is due for a change before you place any orders.

 

[Deere John]

My ex calls for 80w-90 in finals and the best advise I've received is change the oil 2 times more often than manual states as finals have no filter and the metal wear particles are circulated in the oil. Also seems like a good place for a magnet on drain plug.

 

[bob4558]

Im a komatsu mechanic and the pc40 calls for 30w but with more hours switch to the gear lube you will get extra life out of your final drives!

 

[Shannow]

This is variously advertised around the world as a 30, 80W, etc. and is one of my new favourite lubes.

http://www.mobil.com/USA-English/Lubes/PDS/GLXXENCVLMOMobilfluid_424.aspx

 

[widman]

Your decision needs to be based on one thing: Does it have wet brakes in the final drive or not?

If it has wet brakes, you need a TO-4 oil for maximum life and performance. Prior to 1981 that would have been TO-2 which the CD oil would have covered. The TO-4 is a huge improvement over that.

If there are no wet brakes you can put in whatever you want.