My D7E lubrication instructions calls for crankcase oil everywhere including the transmission and finals.
that seeks light. would you pros recommend heavier transmission oil like in other similar vintage machines?

Cat has made changes through the years on oils. I use Cat 30W Transmission/drive train oil in the transmission, Cat 50W Drive train oil in the finals [better if tractor is used in winter],  Phillips 10W Hyd oil in hydraulic system.

Just curious but would the modern Cat 30W TO oil be equivalent to the universal tractor/hydraulic oils widely available today? They typically have a long list of standards they are compatible with on the back of the jugs. It seems the modern practice is to use the universal transmission/hydraulic oil in almost all the compartments of agricultural machinery, even for older machines that used to call for 80-90W gear oil.

I still have "mental" problems using such light oils in a transmission, but the protection is supposedly better than the old thick oils and distributes itself better.

I was told by my father many years ago: "DON'T BE STUPID AND TRY TO SAVE MONEY USING CHEAP OIL!" The price of parts and labor to overhaul sooner than with quality oil is too expensive.
Craig

Cats 30W transmission is formulated to work with steering clutch discs, it eliminates the clutch "chatter" when turning. My thoughts on oil are, if it's a cheap machine use a cheap oil, an expensive machine use an expensive oil.
And change engine oil at 250hrs, transmission and finals at 1000 hrs,  Hydraulic at 2000 hrs.

there is no problem with those universal tractor oils. just use a quality brand name product. the additives of today are so much superior to what these old girls came out with. there is 40 plus years of chemical and lubricant engineering advances.
i personally use caltex textrans tdh in our machine hydraulics and transmission i also used it in the trans and differential of our ford tractor and its suitable for wet brakes. it was specifically for the drivetrain of austoft(case ih) harvesters and in field equipment. in the finals we use caltex torqfluid 454 which has a new name.

if your not sure all the major oil companies have a lube tech advice service contactable by email or phone. get a recommendation from them they know their products backwards the advice is free. some also have the info available in a smartphone app and on thier respective websites.

thank you Rome for those service interval numbers...that sounds very close to what would provide good lubrication and protection..
-and that includes any decent oil available nowadays

You're welcome, also clean the magnetic filters and clean the first stage fuel filter every 250 hrs. There is also a drain plug under the transmission/steering clutch pump to drain about a gallon of engine oil from the accessory drive housing that is not shown in the maintenance manual. Might want to get one of these... CAT Caterpillar D7 D7E OPERATION & MAINTENANCE MANUAL GUIDE BOOK TRACTOR sn 48A | eBay

The Operation and Maintenance Instructions for your model D7E is in the ACMOC library for free.
Craig