Suggestions on changing oil in a bandsaw gearbox with no drain plug

Well after getting my 1957 vintage 16" Do-All band saw reassembled and working, I run into a Powermatic 143. The 143 is a 14" wood/metal band saw with a 2 speed gearbox and 4 speed step pulleys. It has a speed range of 80-3000 fpm. At 400 lbs, it is a lot heavier and stiffer than the Rockwell Delta 14" wood drill press I used to have. I really did not need it but at the price....



My question is in regard to replacing the oil in the two speed gearbox. It has a fill port elbow on the left as shown. It has a max fill plug on the right side as shown. Oddly, every Powermatic manual says to fill it with 1.5 pints of 40 weight oil. But as seen in the photo, the label says to fill to the bottom of the right plug. But there is no drain plug.








The manual calls out 40 weight oil, which correlates to 90W gear oil. Since there is a sleeve bearing in the gearbox, I was concerned about oil additives pitting the sleeve bearing. Fortunately Napa sells 90W GL1 gear oil (part number: NHF 65201) with no additives for about $20/gallon.

Any suggestions of how to change the oil without removing & cracking open the the gearbox? The oil is low and I can see discoloration in some of it. Is it as simple as the following?

fill with oil
run for a while
remove plug
suck oil out with a large syringe with a flexible tube
refill with oil

Thanks!

Grumble grumble...

Well contrary to the manual, there IS a drain plug! That simplifies things. Since I have plenty of oil, would you recommend I flush it once or twice with new oil and then fill it?

Depends on the condition of the oil you drain out, I suppose. Probably not necessary to flush at all, unless it's contaminated by something. Those transmissions don't get hot enough to cause a lot of oil breakdown.

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or flush it out with kerosene and then put oil back, that way you don't waste more expensive oil...

jmm03 said:

or flush it out with kerosene and then put oil back, that way you don't waste more expensive oil...

Click to expand...

Kerosene does work well for cleaning. I am a bit leery of using it around sleeve bearings as the viscosity is so low compared to 90W oil. Since the gallon of oil I have is about 6 oil changes, I flushed it twice with oil. I really amazed how dark the oil was from the first flush. But as expected it was pretty clean on the second flush.

Thanks for the comments. Now to get it cleaned up and tires installed.