Non detergent oils in gearboxes, etc.

[KentuckyEd]

We have several pump applications with gearboxes and bearing cases where the manufacturer specifies using non detergent oil. I can't get a straight answer as to why. Can anyone explain why this is recommended for these non combustion applications? Is it OK to use a detergent oil anyway? All of our applications start as new installations so the equipment is clean and new when installed and we're talking about initial fill of these systems.
Thanks in advance, Ed

 

[unDummy]

What type of pump/gearbox/bearings?

I think that some companies are archaic with fluid recommendations. I don't see any reason why a detergent oil can't be used. I believe the old way of thinking is that a non-detergent oil is straight weight and less shear prone. Most newer motor oils are pretty shear prone.
The only thing that I see that might not be good is the reduced level of certain additives in newer motor oils. The typical straight weight oils, and the race, HDEO, or motorcyle oils, don't always have EPA happy levels of AW/EP additives. The manufacturer recommendations might be assuming that most straight weight oils have a good ol' dose of ZDDP, or that non-detergent oils have more oil and less non-needed additives(like detergents, pour point depresents, viscosity index improvers...).

So, it comes down to the type of machinery, the loads that are present, the temperature that the oil typical runs at, and type of contamination. I wish that manufacturers would provide oil weight range and additive level recommendations, instead of just recommending certain oil types.

 

[XS650]

The common reason given is that detergents tend to hold contaminants in suspension and the machinery that specs non-detergent oils doesn't have significant filtration so they want the contaminants to drop out and stick in the goo in the bottom of the reservoir.