Small Machine Oil

[Langanobob]

I have several older small machine tools that have bearings, shafts and a few gears. The old manuals usually call for SAE 30 oil. The machines are old and were built before detergent oil existed. Conventional wisdom says to use non-detergent oil in these machines because detergent oil will hold debris in solution. These machines don't have combustion chambers so there's no combustion byproducts to end up in solution and I don't think detergent oil will hold metal particles in solution. I have a couple of questions.

1. Is there any good reason not to use detergent oil in these small old machines? This is sort of an academic question since I have non detergent machine oil on hand, I would just like to understand the non-detergent oil requirement.

2. I've been told that detergent oil is more hydroscopic than non-detergent and will pick up moisture which will in turn cause foaming and lubrication failure. Is this true? Is detergent oil actually more hydroscopic than non-detergent and if so, is it really a problem? These machines don't get hot enough to drive off significant moisture.

Appreciate comments and answers.

Thanks,

Bob

 

[JHZR2]

This is a good question, as we are thinking the same for the mechanism on our coal stoker. It is easy to get HD 30 or HD 40, but our ND 40, which was the spec, came with the stoker 25 years ago, and is somewhat tough tofind at the auto parts store...

 

[bruce381]

Just buy some ISO 100 Hydraulic oil will work fine or use a ND 30wt or even use a regular 30wt will work. YES if wet the detergents may hold water BUT they also will have a better rust inhibitor. I have never seen or heard of problems with machine tools using "modern" detergent type oils. Machine tools DO NOT mormally have a lot of gunk that a detergent will knock loose and even if they do a detergent oil is NOT a solvent. Use whatever you can find in the right vis grade and change it at a normal interval and do nor worry about it. In older machine the BIGGEST problem is LEAKS keep them full.
bruce

 

[Langanobob]

Bruce,

Thanks for your reply. I already have numerous grades of non-detergent machine oil, just wanted an explanation about the use of detergent oils, and I think you explained pretty well.

Bob

 

[rclint]

I know this is an old post, but I wanted to drive home the use of hydraulic oils in place of the machines which called for SAE 30 non detergent oils. If you have a tractor supply, or similar close by it's cheaper to but the hydraulic oils many times than it is the non detergent oils. I use ISO 46 in a small lathe which calls for a non detergent oil. It has Timken bearings, and I'm sure $$$ each maybe more !! It has a flow through oil system that is oiled before each use.