View Full Version : Another gear oil question

GA D8 2U
12-22-2006, 07:55 PM
I have a D8 2u that I want to change the oil in the transmission and final drives. What is the correct weight oil to use for the transmission and for the final drives?

As for the engine, I have been told that a 40w was always used in the engine. I plan to change this oil also.

The next time I have the D8 out of the barn I will take some pictures to post of the tractor and also of the pull scraper that I have, which I need some help on.

If climate is a factor in what weight oil, I live in west central Georgia. A cold day to work outside around here is temps in the low 20s.

dave morgan
12-22-2006, 10:24 PM
this will get you close
Rotella 15W40 in engine, can be ran in transmission too if it has a filter and lube pump to supply oil to all gears and bearings.

Final drive has no lube pump or filter, and most run 50W engine oil there...we are thinking of changing to synthetic in the final drives...in the old days they ran 90W in the finals, but most books have changed that by now.

12-25-2006, 04:20 PM
I run 140 w green mineral oil in my old cats. They only get run in the spring summer and early fall. the 140w leaks less out of bad seals than the 90w. My oil supplier said this is the best oil for me to use bc the new hp lubes could potentially damage brass and bronze that may be in the bearings. the degergents in the new hp lubes will also make leaks worse. The green mineral oil is detergent free and therefore does not break down or become acetic. Everyone has different ideas but i hope this helps you some.
Beau nelson

12-25-2006, 11:13 PM
30 or 40 wt in the engine, do not use a multi vis oil in these old engines, 90 wt in the trans and finals, unless you have a little seepage then I would use the 140 in the finals.

12-25-2006, 11:26 PM
I have used 15W-40 in the D4 and 112 (both are 315 engines) for many, many years and have never had any problems. It keeps them squeaky clean too!! I use the same engine oil in them that I use in my Green machines!! For tranny and finals I use 90W. I never run them below 0 degrees F as it is too cold anyway!!

GA D8 2U
12-26-2006, 07:25 AM
Thanks everybody for the info.

After reading some of the respondes I have another question. I assumed what is in the trans right now is maybe 90w. The trans does have a filter. Would a 90w oil flow okay thru this filter with out crushing it?

If the weather is good New Years day I plan to do an oil change and get some pictures.

12-26-2006, 05:53 PM
you shouldn't have any problem with gear oil running thru a filter. The rear axle in my freightliner truck (front one ) has a filter mounted on it and it is the same filter chevrolet uses for an oil filter on their engines. I am running 140 wt and change the filter every 50 thousand miles or so.


Old Magnet
12-26-2006, 08:39 PM
Either 90wt for average ambient temperatures or 140wt in hot climates is correct.

12-27-2006, 08:33 AM
30 or 40 wt in the engine, do not use a multi vis oil in these old engines, 90 wt in the trans and finals, unless you have a little seepage then I would use the 140 in the finals.

I have a pamphlet distributed by Caterpillar from the 50's on service and care of D2's-D8's in a illustrated cartoon format and it specifically says not to use a straight weight oil in the engines as it needs the additives to remove carbon and other deposits. The general rule of thumb I was always told was if the engine has a full flow filter, ie from the pump directly to the filter, use a multi-grade oil as the particles will stay in suspension and be trapped in the filter. If the engine does not have a filter, like some old gas tractors, use straight weight so the particles can settle out and be drained with oil.

12-27-2006, 12:06 PM
I'm a little confused. I always understood the issue with the filter fitted engines was detergent in the oil to keep particles in suspension so the filter can do it's thing. I thought the multi viscosity was developed to allow a greater range of operating temps??? :confused:

Happy new year to all

12-27-2006, 12:30 PM
I agree with Tom that if the critter has a filter, use detergent oil, if no filter, use non detergent. The multivis oils were to give "more constant viscosity" over a greater range of temps. Multi viscosity oils are sort of misnamed as they're not really multi viscosity oils at all but exhibit similar characteristics at low and high temps as their wts designate. 5W-30 means it exhibits characteristics of "5" wt oil in winter and "30" wt in summer( about 100 degrees C)

12-27-2006, 01:07 PM
You guys are correct, I sometimes confuse myself with my own ramblings. Straight weight does not mean non-detergent. As long as a detergent oil is used everything is okay. It just makes things a little stiff when the temp gets cold.

12-27-2006, 02:05 PM
They change the designations of oils at times but when I was dealing with Cats for years the oil used in the engines was Series-3 #30 in your case. Today I don,t know what the name or type is for it & there also was #10 Series-3 oil back then too for cold weather or whatever. Today you hear of the 15-40 oil being used instead of the single grade now.