Our purchasing department want to change our oil supplier from Mobil to Houghton.
Some oils we use are Mobil DTE light, and Mobil DTE 24, both oils have a viscocity of 32 but the DTE light is a circulating oil and we use this oil on precision bearing spindles with a speed of 10000rpm and the DTE 24 we use for our smaller hydraulic tanks such as horizonral CNC lathes, on our larger units we use DTE 25.
Houghton wants to sell us Hydro HP 32 to replace both of these oils.
Can someone tell me if this is the right thing to do and if not why not.

If you are changing just due to costs then talk to your Mobil contact.
Some rationalisation could be done to improve your lubrication eg you could use DTE 24 in the DTE light applications. DTE 24 is one of the best hydraulic oils in the marketplace and provides cost benefits in terms of extended oil life and component life.

Try out Chevron Hydraulic Oil AW or Caltex Rando HD series oil with the viscosity grades you require.

All mentioned oils are good oils (although I cannot say the same for Houghton’s because I am not familiar with their oil, but that doesn’t mean they are not good oils), and whichever oil you end up with may serve you well. However, if you do change your oil, make sure new oil is compatible with what you have now, because, if incompatible, you are going to be up for a challenge to keep your operation smooth and trouble-free. The test is ASTM D7155-06, and if you don’t want lab to run the full test, as a minimum, request a Tier 1 part to be done.

TAN of hydraulic oil new should be always less than 1.
Our DNR Corp HYD oil68 has TAN of 0.00022 means if it gets mixed with metal working fluid than also it will not contaminate MWF.Hence life of MWF will increase drastically. In case of injection machines this oil will outperform because to reach tan of more than 1 it will take around 10000 hrs.

DNR Corp
91 22 9820229229.

If you review the Technical Data of the Hydro HP its pretty easy to prove you've taken a step back. I guess the old adage "you get what you pay for" rings true. I'm sure it will be fine if you change it often enough, but that destroys the whole cost savings behind getting a cheaper product. The test data is insufficient and the text is vague. It's been my experience when the TD sheet lacks info, the company trying to mislead the reader.