{"product_id":"castair-synthetic-oil-for-rotary-screw-compressors-fg4000","title":"Castair Synthetic Oil for Rotary Screw Compressors FG4000","description":"\u003cp\u003eThe Castair FG4000 is a 5-gallon container of full synthetic lubricant formulated specifically for Castair rotary screw air compressors. This is the factory-recommended lubricant for Castair rotary screw units, rated for a 1-year or 4,000-hour service life under normal operating conditions. If you run a Castair rotary screw compressor, this is the oil it was designed to run on.\u003c\/p\u003e\n\n\u003ch2\u003eWhy Rotary Screw Compressors Need the Right Oil\u003c\/h2\u003e\n\u003cp\u003eRotary screw compressors operate differently from piston compressors. The oil in a screw compressor does more than lubricate — it seals the compression chamber, carries away heat, and is continuously cycled through an oil separator before the compressed air leaves the unit. Using the wrong oil type causes foaming, varnish buildup on internal surfaces, premature separator failure, and oil carryover into your air system.\u003c\/p\u003e\n\u003cp\u003eThe FG4000 is a full synthetic formulation designed to handle the high operating temperatures and continuous-duty cycles that rotary screw compressors run at. It resists varnish and carbon deposit formation, stays stable at elevated temperatures, and does not foam under the continuous agitation of screw operation.\u003c\/p\u003e\n\n\u003ch2\u003eKey Specifications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e FG4000\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSize:\u003c\/strong\u003e 5 gallons\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eType:\u003c\/strong\u003e Full synthetic\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Castair rotary screw air compressors\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eService Life:\u003c\/strong\u003e 1 year or 4,000 hours (whichever comes first)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eAvailable Sizes\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eGA4000\u003c\/strong\u003e — 1 gallon (topping off or single-fill service)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFG4000\u003c\/strong\u003e — 5 gallons (full drain-and-fill service, shop stock)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe 1-gallon GA4000 makes sense for topping up oil level between service intervals. The 5-gallon FG4000 is the right quantity for a full oil change on most Castair rotary screw units and for shops that want to keep a service supply on hand without repeated ordering.\u003c\/p\u003e\n\n\u003ch2\u003eCastair Oil Lineup — Piston vs. Rotary Screw\u003c\/h2\u003e\n\u003cp\u003eCastair makes oil for both compressor types, and they are not interchangeable:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCAST-LUBE (QT5W30 \/ GA5W30)\u003c\/strong\u003e — Semi-synthetic, for piston compressors. 4-month or 400-hour rating.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCAST-LUBE (QT10W30 \/ GA10W30)\u003c\/strong\u003e — Full synthetic, for piston compressors. 8-month or 800-hour rating.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFG4000 \/ GA4000\u003c\/strong\u003e — Full synthetic, for rotary screw compressors only. 1-year or 4,000-hour rating.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eDo not use piston compressor oil in a rotary screw unit. Piston compressor oil will foam under the continuous oil cycling and higher operating temperatures of screw machines, causing separator failure and oil carryover into the air system.\u003c\/p\u003e\n\n\u003ch2\u003eIf Your Rotary Screw Has Varnish Buildup\u003c\/h2\u003e\n\u003cp\u003eCastair also offers Varnasolv rotary varnish cleaner for units that have accumulated varnish from incorrect oil or extended service intervals. Procedure: mix Varnasolv at 10%, run 50 hours, drain oil while warm, then change oil and separator filters. Do not skip the separator filter change — varnish-contaminated separators restrict airflow and cause oil carryover even after the oil is clean.\u003c\/p\u003e\n\n\u003ch2\u003eWhen Does a Shop Need This\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eAnnual oil service on a Castair rotary screw compressor\u003c\/li\u003e\n\u003cli\u003eOil change after running contaminated or incorrect oil\u003c\/li\u003e\n\u003cli\u003eStocking shop supply for a Castair rotary screw maintenance program\u003c\/li\u003e\n\u003cli\u003eInitial fill after rotary screw pump service or rebuild\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe 4,000-hour rating translates to roughly 1-2 years of shop use depending on daily run time. Set a calendar reminder and stick to the interval — extended oil service on a rotary screw is the most common cause of premature separator and bearing failure.\u003c\/p\u003e\n\n\u003ch3\u003eWhy Buy From OEM Diagnostic Tools?\u003c\/h3\u003e\n\u003cp\u003eOEM Diagnostic Tools has supplied professional shop equipment and components since 2016. We stock Castair lubricants so you can get the factory-recommended oil without going through distributor channels. Free shipping on qualifying orders, free tech support at 866-217-0063, and full manufacturer warranty. Call us if you need to confirm the correct oil for your specific Castair rotary screw model.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCall 866-217-0063 for quick answers and help!\u003c\/strong\u003e\u003c\/p\u003e","brand":"Cast Air","offers":[{"title":"Default Title","offer_id":53342498128085,"sku":"FG4000","price":664.56,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0622\/8466\/0949\/files\/OIL_new_700x_7a226070-b229-45d9-9795-5abc9528078e.webp?v=1772652428","url":"https:\/\/aircompressorfactorydirect.com\/products\/castair-synthetic-oil-for-rotary-screw-compressors-fg4000","provider":"Air Compressor Factory Direct","version":"1.0","type":"link"}