What is a clean sump actually worth? Tramp oil shortens coolant life — skim it off and you dump coolant less often, which saves on disposal, labor, and concentrate. This estimates your payback on a skimmer using conservative, sourced assumptions. We deliberately leave out tool-life and scrap savings — they’re real, but too shop-specific to put an honest number on. Put in your numbers:
Your numbers are pre-filled with conservative defaults — adjust any of them.
What’s behind the math (so you can trust it)
- Removing tramp oil extends sump life because oil seals the coolant from air and feeds the bacteria that turn a sump rancid (Ohio EPA, WA Dept. of Ecology). We use a conservative 1.5× life extension — skimmer makers report up to 2×, we use less.
- The coolant you buy is only about a quarter of what a sump of coolant really costs you over its life — maintenance, disposal and energy are the rest (peer-reviewed lifecycle study, Int. J. Adv. Manuf. Technol. 2007). So this leads with the disposal + labor savings, not the fluid.
- Disposal at $0.75/gal assumes bulk pickup. Single drums often run $5–$9/gal after minimum trip fees — bump that field if that’s you, and the payback improves a lot.
- Savings = (changes you avoid per year) × (cost of one change). Payback = skimmer cost ÷ annual savings.
Shop skimmers & coalescers →
Estimates only; your results vary. Conservative defaults from independent sources (peer-reviewed coolant lifecycle study 2007; Ohio EPA Fact Sheet #11 & WA Ecology on tramp oil; NIOSH on metalworking-fluid health). We intentionally exclude tool-life, scrap-rate and productivity gains — they’re real but not honestly reducible to one number for your shop.