Type of oil for final drive

I just purchased my first mini ex. Just about to change all the fluids and filters before I bring it up to the island for cabin construction. I have everything figured out for the filters and fluids except for the final drive. My machine is an early 90s Kobelco SK024. Do finals take a standard lubricant or is it specific machine to machine? I have tried searching on the internet for the answer but due to the age of the machine it is difficult to find any information as it was born before the digital age. Anyone have any recommendations? if not who would be a good person to contact to find out what it requires?

80W-90 gear oil

http://www.finaldrivecenter.com/Service.htm

On your page it says esso spartan ep220 too, is it also good oil. I have a kobelco sk35sr 2

Yes, that is good.

Per Kobelco service manual:

I don't know how it effected machines long term, but I worked for a very large corporation that had hundreds of millions of dollars worth of large equipment and we used 15W40 Delvac in darn near everything; hydraulic, steering, differentials, you name it. It sure made it easier for the lube trucks. Pretty well everything that didn't have a grease zerk on it or say "Diesel Fuel Only" 15W40 went in. I have to admit that I was quite surprised at the lack of failures based on what I'd been taught.

Well, we used to pack grease in wheel bearings, now they run in gear oil with oil hubs. Lighter oil will sometimes get to where it's supposed to when heavier lubes don't. The planetary finals I've been into all seem to treat the lubrication of the bearings for the planetary gears as a sort of "wishful thinking" exercise from the look of the passages the oil had to get through to keep the bearings happy. CAT excavators I believe use 50 weight which is what I usually advocate for the planets in the machines I deal with, CAT TDTO-50. YMMV, when in doubt us what the manufacturer says though!

I'd go with lantraxco I found 50 weight in a small excavator works well and I change the final oil when I I change the engine oil and if it's dirty I do an sos or probe to make sure all is ok

A company I work for years ago operating a pc 220 -5 in logging we used to use engine oil in there as well and never had a failer