Question 1

Are PAG lubricants compatible with standard mineral oils?

Accepted Answer

No, traditional PAG lubricants are highly polar and completely incompatible with non-polar mineral oils and polyalphaolefins (PAO). Mixing them leads to phase separation, rapid viscosity increase, filter clogging, and lubrication failure, requiring a thorough system flush before switching.

Question 2

Which seal materials are compatible with polyalkylene glycol fluids?

Accepted Answer

Fluorocarbon elastomers (Viton/FKM), fluorosilicone, and PTFE exhibit excellent PAG seal compatibility. Standard Nitrile (NBR) can sometimes be used with water-insoluble PAGs under mild temperatures, but should be avoided with water-soluble PAGs.

Question 3

Do PAG base oils damage internal industrial machine paints?

Accepted Answer

Yes, synthetic PAGs act as strong solvents and can soften or dissolve conventional industrial paints and varnishes used inside reservoirs. Internal surfaces should be left unpainted or coated with chemical-resistant epoxy or polyurethane coatings.

Question 4

What is the procedure for switching a gearbox from mineral oil to PAG?

Accepted Answer

Drain the mineral oil completely while warm. Flush with a low-viscosity flushing PAG, clean or replace all filters, and verify all seals and paint coatings are fully compatible. A thorough flush prevents contamination and ensures synthetic performance.

PAG and Lubricant Compatibility Checker

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