--- title: Donaldson Hy-Pro Lube & Hydraulic Filtration Industry Blog | ISO Fluid Cleanliness Codes description: ISO Fluid Cleanliness Codes | Learn about hydraulic fluid, lube oil, diesel fuel and industrial fluid contamination, filtration and conditioning on the Donaldson Hy-Pro blog. --- [![Donaldson Hy-Pro Logo_White](https://www.hyprofiltration.com/hs-fs/hubfs/Hy-Pro%20Logos/Donaldson%20Hy-Pro%20Logo_White.png?width=591&height=265&name=Donaldson%20Hy-Pro%20Logo_White.png) ![Donaldson Hy-Pro Logo 2](https://www.hyprofiltration.com/hs-fs/hubfs/Hy-Pro%20Logos/Donaldson%20Hy-Pro%20Logo%202.png?width=584&height=262&name=Donaldson%20Hy-Pro%20Logo%202.png) ](https://www.hyprofiltration.com) [**](https://www.hyprofiltration.com/blog/topic/iso-fluid-cleanliness-codes#tmpmodule_1568675152246189) [![Distributors](https://no-cache.hubspot.com/cta/default/170326/6a993b6f-f737-4a22-8a35-a45c4da5c3b4.png)](https://cta-redirect.hubspot.com/cta/redirect/170326/6a993b6f-f737-4a22-8a35-a45c4da5c3b4) ![ECATALOG](https://no-cache.hubspot.com/cta/default/170326/interactive-162302555948.png) ** ###### 9 min read ### [Understanding ISO 4406 Cleanliness Codes: A Complete Guide to Fluid Contamination and Reliability](https://www.hyprofiltration.com/blog/iso-4406-cleanliness-codes) By [Donaldson Hy-Pro Marketing](https://www.hyprofiltration.com/blog/author/donaldson-hy-pro-marketing) on Wed, Dec. 03, 2025 [![](https://www.hyprofiltration.com/hubfs/Copy%20of%20Copy%20of%2024%20Hour%20Turnaround%20Case%20Study%20Banner%20(2).png) ](https://www.hyprofiltration.com/blog/iso-4406-cleanliness-codes) ###### Topics: [contamination](https://www.hyprofiltration.com/blog/topic/contamination) [fluid cleanliness](https://www.hyprofiltration.com/blog/topic/fluid-cleanliness) [ISO Fluid Cleanliness Codes](https://www.hyprofiltration.com/blog/topic/iso-fluid-cleanliness-codes) [filter elements](https://www.hyprofiltration.com/blog/topic/filter-elements) [cleanoil](https://www.hyprofiltration.com/blog/topic/cleanoil) [hydraulic oil cleanliness](https://www.hyprofiltration.com/blog/topic/hydraulic-oil-cleanliness) [hydraulic oil maintenance](https://www.hyprofiltration.com/blog/topic/hydraulic-oil-maintenance) [lubrication systems](https://www.hyprofiltration.com/blog/topic/lubrication-systems) ###### 2 min read ### [24-Hour Turnaround: How Clean Oil Restored Production at a U.S. Paper Mill](https://www.hyprofiltration.com/blog/24-hour-turnaround-how-clean-oil-restored-production-at-a-u.s.-paper-mill) By [Donaldson Hy-Pro Marketing](https://www.hyprofiltration.com/blog/author/donaldson-hy-pro-marketing) on Wed, Nov. 05, 2025 [![](https://www.hyprofiltration.com/hubfs/24%20Hour%20Turnaround%20Case%20Study%20Banner%20(2).png) ](https://www.hyprofiltration.com/blog/24-hour-turnaround-how-clean-oil-restored-production-at-a-u.s.-paper-mill) ###### Topics: [contamination](https://www.hyprofiltration.com/blog/topic/contamination) [fluid cleanliness](https://www.hyprofiltration.com/blog/topic/fluid-cleanliness) [ISO Fluid Cleanliness Codes](https://www.hyprofiltration.com/blog/topic/iso-fluid-cleanliness-codes) [filter elements](https://www.hyprofiltration.com/blog/topic/filter-elements) [cleanoil](https://www.hyprofiltration.com/blog/topic/cleanoil) [hydraulic oil cleanliness](https://www.hyprofiltration.com/blog/topic/hydraulic-oil-cleanliness) [hydraulic oil maintenance](https://www.hyprofiltration.com/blog/topic/hydraulic-oil-maintenance) [lubrication systems](https://www.hyprofiltration.com/blog/topic/lubrication-systems) ###### 6 min read ### [How Dirt Makes Dirt: The Hidden Cost of Particulate Contamination](https://www.hyprofiltration.com/blog/dirtmakesdirt) By [Donaldson Hy-Pro Marketing](https://www.hyprofiltration.com/blog/author/donaldson-hy-pro-marketing) on Wed, Apr. 16, 2025 [![](https://www.hyprofiltration.com/hubfs/Dirt%20Makes%20Dirt%20Blog%20(300%20x%20175%20px).png) ](https://www.hyprofiltration.com/blog/dirtmakesdirt) ###### Topics: [dirt](https://www.hyprofiltration.com/blog/topic/dirt) [ISO Fluid Cleanliness Codes](https://www.hyprofiltration.com/blog/topic/iso-fluid-cleanliness-codes) [cutdirtcutcosts](https://www.hyprofiltration.com/blog/topic/cutdirtcutcosts) [cleanoil](https://www.hyprofiltration.com/blog/topic/cleanoil) ###### 2 min read ### [Copper Mine Achieves Amazing Results with Donaldson Hy-Pro](https://www.hyprofiltration.com/blog/copperminecasestudy) By [Hy-Pro Marketing](https://www.hyprofiltration.com/blog/author/hy-pro-marketing) on Tue, Jul. 23, 2024 [![Copper Mine Promo for Email (9)](https://www.hyprofiltration.com/hs-fs/hubfs/Copper%20Mine%20Promo%20for%20Email%20(9).png?width=750&height=288&name=Copper%20Mine%20Promo%20for%20Email%20(9).png)](https://www.hyprofiltration.com/hy-pro-increased-papermill-filter-lifespan-case-study) ##### A new case study is available now! ###### Topics: [ISO Fluid Cleanliness Codes](https://www.hyprofiltration.com/blog/topic/iso-fluid-cleanliness-codes) [case study](https://www.hyprofiltration.com/blog/topic/case-study) [cutdirtcutcosts](https://www.hyprofiltration.com/blog/topic/cutdirtcutcosts) [cleanoil](https://www.hyprofiltration.com/blog/topic/cleanoil) [Copper Mine](https://www.hyprofiltration.com/blog/topic/copper-mine) ###### 3 min read ### [Hy-Pro Filtration Helps Paper Mill Achieve 75% Cleaner Oil](https://www.hyprofiltration.com/blog/papermillcasestudy) By [Hy-Pro Marketing](https://www.hyprofiltration.com/blog/author/hy-pro-marketing) on Tue, Dec. 05, 2023 [![META IMAGE case study](https://www.hyprofiltration.com/hs-fs/hubfs/META%20IMAGE%20case%20study.gif?width=739&height=283&name=META%20IMAGE%20case%20study.gif)](https://www.hyprofiltration.com/hy-pro-increased-papermill-filter-lifespan-case-study) ##### A new case study is available now! ##### With the help of Hy-Pro Filtration, a U.S. Paper Mill was able to achieve 75% cleaner oil.  ###### Topics: [ISO Fluid Cleanliness Codes](https://www.hyprofiltration.com/blog/topic/iso-fluid-cleanliness-codes) [case study](https://www.hyprofiltration.com/blog/topic/case-study) [paper mill](https://www.hyprofiltration.com/blog/topic/paper-mill) [cutdirtcutcosts](https://www.hyprofiltration.com/blog/topic/cutdirtcutcosts) [cleanoil](https://www.hyprofiltration.com/blog/topic/cleanoil) ###### 2 min read ### [Factory Side Chat Podcast, Episode 9, Reducing the Total Cost of Ownership with a Kidney Loop or Offline Filtration unit](https://www.hyprofiltration.com/blog/factorysidechatepisode9-0) By [Hy-Pro Marketing](https://www.hyprofiltration.com/blog/author/hy-pro-marketing) on Fri, Aug. 26, 2022 [![](https://www.hyprofiltration.com/hubfs/episdode%209%20factory%20side%20chat.png) ](https://www.hyprofiltration.com/blog/factorysidechatepisode9-0) ## Hy-Pro's Factoryside Chat is now available on Apple Podcasts, Spotify, Podbean, and YouTube. ###### Topics: [fluid cleanliness](https://www.hyprofiltration.com/blog/topic/fluid-cleanliness) [ISO Fluid Cleanliness Codes](https://www.hyprofiltration.com/blog/topic/iso-fluid-cleanliness-codes) [cleanliness](https://www.hyprofiltration.com/blog/topic/cleanliness) [hydraulic oil](https://www.hyprofiltration.com/blog/topic/hydraulic-oil) [Podcast](https://www.hyprofiltration.com/blog/topic/podcast) [Factoryside Chat Podcast](https://www.hyprofiltration.com/blog/topic/factoryside-chat-podcast) [cutdirtcutcosts](https://www.hyprofiltration.com/blog/topic/cutdirtcutcosts) [kidney loop](https://www.hyprofiltration.com/blog/topic/kidney-loop) [All posts](https://www.hyprofiltration.com/blog/all) ### Featured ### Sign up for updates ## Have a Question for Donaldson Hy-Pro? 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