Watermaker pump oil: unusual type for Echotec?

[ohthetrees]

I have a Echotec 1300-PRO-3 AC watermaker that I doubt the previous owner ever changed the watermaker pressure pump oil.

I'm having a terrible time figuring out what type of oil to buy.

It seems most (non pressure-recovery type) pressure pumps I see take 30W oil. Sometimes I see "Type 100" or "ISO 68" recommended as well, but I don't know what those are. However, my Echotec has the following recommendation:

"SAE 90 non-detergent gearbox oil"

Additionally I found the following info from Echotec:

"The brand is not critical, once it is SAE-90 non-detergent gear oil. We typically sell Bel-Ray. Yamaha Yamalube is similar."

A MSDS was attached, which I've attached to this post.

The problem is I just can't find any Bel-Ray nor Yamalube which is plain old SAE-90 non-detergent. Every 90w oil I can find is GL-4 or GL-5, which my understanding has EP pressure additives. The only non-detergent oil I can find is 30w, which seems like most pressure pumps want, but not mine?

Can anyone shed light on the situation? Can I use the 30w non-detergent oil? Or can someone point me to a place to buy the proper oil?

Thanks!

[EngineerRetired]

Just about any tractor (home and farm store) supply house will have it.

[ohthetrees]

Thank you. I think there is some confusion about weights. I understand that a 30w engine oil has a similar weight to a 90w gear oil. So I'm wondering if all these 30w non detergent pressure pump oils I'm finding might be just the thing I need.