I just got an old Craftsman 108-22920 horizontal bandsaw, and I need to top off the oil in the hydraulic cylinder that regulates the feed speed. The manual calls for SAE 20 oil, but I only have SAE 30. Is there enough of a difference in this application for me to bother getting the specified grade, or can I go ahead and use what I have?

It's just gravity feed right? The thicker oil will probably slow it down some. As long as it's not going through a pump you should be fine.

Yes, it’s just gravity pulling the frame down that moves oil from one chamber to the other; no pump involved. Well, slower is better than too fast, I guess. Thanks. 

If it runs too slow thin it with a little WD40.

The cylinder seems to do its job in the bottom half of its range, which is probably all I’ll need in general. Filling it is tricky, as the hole is pretty tiny and hard to access. There also appears to be a leaking seal, as I’m getting oil bubbling around the shaft. Well, we’ll see how it goes once the blade arrives. 

I use ATF in mine, it's easier to get through the filler. Bleed it by cycling it up and down with the needle valve wide open, it'll bleed itself. It's easy to compensate for oil weight with the needle valve feed adjustment. 

You can tighten the packing nut on the end of the cylinder a LITTLE BIT, 1/4 turn MAX, if that doesn't stop the leaking it's just an O ring. Take the nut off and replace the O ring. 

Nice score, Use a good square to check the blade, they adjust easily but don't get carried away 1/4 turn is TOO much at once or you'll be chasing it back and forth till you're crazier than you are now. 

Frosty The Lucky.

Others have given good advice on the cylinder.  What I wanted to add is the joy of a good quality blade vs the nightmares of a crap quality blade.  Don't be tempted by low prices--it's worth a little extra to get a good Starrett, Lenox or other top brand here. "No name" in Chinese is definitely out.   I personally prefer variable tooth pitch but with blades, everyone is going to have a different opinion.

Get a pack of cheap dollar store toothbrushes (or similar) and a good rare earth magnet and make yourself a blade wiper to go on the outboard end. Heat and form the toothbrush handle as needed, stick in place with good magnet.   Even with coolant flushing, I find that a very light wipe (barely touching) of any long stringy bits that get caught in the blade teeth makes a huge difference in frustration and the ability to walk away from the machine without worrying about the blade binding. 

I've got a Starrett blade on order, an "Intenss Pro-Die" with 10/14 variable pitch. According to the product description, it's appropriate for "cutting low alloy steel; aluminum; stainless steel; carbon steel; tool, die, and mold steel; steel up to C45 Rockwell hardness; nickel-based alloys; and nonferrous metal." It's a bimetal blade with M42 high-speed steel teeth.

1 hour ago, Frosty said:

till you're crazier than you are now. 

It's so wonderful when people really understand you.

Update: figured out that I could take out the filler screw, remove the stem for the needle valve, pour oil down the valve tube until it started to come out of the filler hole, reinsert the stem, and reinsert the screw. Seems to have worked just fine, and the cylinder looks to be doing its job well. 

We've clicked since we met, a brother from another Mother. 

Come to think of if my real brother's from another Mother.

Good solution filling the hyd cylinder, I'm going to remember it.

Frosty The Lucky.

Well, my mother is Alaskan!