Can I mix two different Bushingo impregnation oils in one bushing?

Avoid mixing families where possible. Each oil carries its own additive and viscosity balance, and combining them can cancel additive performance or shift the effective viscosity. If a top-up or re-impregnation is needed, use the same oil the bushing was originally charged with, or specify a single replacement grade for the whole batch.

How do I know which oil my bushing was impregnated with?

It is defined at order, not read off the part, since the oil is inside the pores. Record the oil family (PE1152, TURBO T100, METADOP or PE1116) against the SKU at specification time so re-orders and any future re-impregnation stay consistent.

Does a higher-viscosity impregnation oil always carry more load?

Broadly within this class it improves film load capacity and resistance to squeeze-out, which helps slow, heavily loaded or oscillating duties. But it also raises starting torque and slows film re-formation, so for high-speed or cold-start work a lighter oil such as PE1116 often performs better overall.

Impregnation Oils Explained: PE1152, TURBO T100, METADOP, PE1116

The defining feature of an oil-impregnated sintered self-lubricating bushing is that the lubricant is not applied to the surface but stored inside the component. During manufacture the porous metal skeleton, typically retaining around 20-25% interconnected porosity for sintered bronze, is vacuum-impregnated so that oil fills the pore network. In service the bushing behaves as its own reservoir: the oil does the running, the metal simply carries it and provides the load path. Choosing the correct impregnation oil is therefore as important as choosing the matrix grade, because the oil governs film formation, friction and the usable temperature window.

How the oil actually reaches the running surface

Sintered bearings exploit a thermal-capillary mechanism. At rest the pores hold oil by capillarity. When the shaft rotates, local frictional heating and the pressure difference generated in the converging gap between shaft and bore draw oil out of the pores and onto the bearing surface, where it forms a hydrodynamic or mixed-lubrication film. When motion stops and the interface cools, capillary action and surface tension pull the oil back into the matrix. This reversible "bleed and reabsorb" cycle is what makes the bearings maintenance-free and dry-running in the sense that no external lubrication is required, only an intact internal charge. The oil's viscosity, viscosity-temperature behaviour and surface tension directly control how readily this exchange occurs.

Why viscosity grade matters for the class

Viscosity is the first selection criterion. A lower-viscosity oil migrates and re-forms its film more easily, which favours high rotational speed, cold starts and low-torque instruments. A higher-viscosity oil carries more load and resists being squeezed out of the contact, which favours heavy radial duty and slow oscillation. Because the oil sits inside a fixed pore geometry, the grade also affects how much lubricant the same bushing can release per revolution. This is why the same BP25 sintered bronze blank can be specified with different oils for very different applications without changing its dimensions.

The Bushingo impregnation oil families

Bushingo offers a small, deliberately differentiated range so that the matrix and the oil can be matched to the duty rather than compromised across it:

PE1152 - a general-purpose mineral impregnation oil intended as the default charge for a broad span of sintered bronze and sintered iron bushings. It balances film strength and mobility, making it a sensible starting point for standard rotating and lightly oscillating duties where no special thermal or speed extreme applies.
TURBO T100 - a turbine-type oil built around oxidation stability and clean running. Turbine oils are formulated to resist thermal-oxidative ageing and to shed water and deposits, which suits bushings that run warm or for long uninterrupted periods where varnish and sludge formation inside the pores would otherwise be the failure mode.
METADOP - an oil geared toward higher-duty contacts, where additive support improves boundary behaviour under mixed lubrication. It is the choice when the film is intermittently thin - slow speeds, higher unit loads or frequent stop-start - and metal-to-metal contact at asperities must be managed.
PE1116 - a lighter member of the PE family suited to lower-viscosity duties: higher speeds, finer clearances and instrument or light-mechanism work where low starting torque and rapid film re-formation matter more than maximum load capacity.

Matching oil to matrix and duty

As a working guide within this class of self-lubricating bearings, three questions drive the choice. First, is the duty speed-dominated or load-dominated? Speed-dominated work leans toward the lighter oils (PE1116, PE1152); load- and boundary-dominated work leans toward METADOP. Second, will the bushing run warm or for long continuous shifts? Oxidation stability then becomes decisive and points toward a turbine-type oil such as TURBO T100. Third, is the application a standard commodity duty with no extreme? PE1152 is then the pragmatic default. Sintered bronze bushings of this type typically operate to around 100 C continuous with mineral charges; the oil chemistry, not the bronze, usually sets the practical upper limit, so a thermally stable oil widens the safe envelope.

Practical points that protect the oil charge

Because the lubricant is finite, installation and handling should preserve it. Press bushings with the correct arbor and closed tooling rather than open jaws, since crushing the bore can partially close the surface porosity and reduce oil bleed. Avoid solvent flushing or aggressive degreasing of a finished bearing, which strips the internal charge. Keep bushings in sealed packaging until fitting so the pores stay full. Where a duty is genuinely severe, re-impregnation or a supplementary compatible oil of the same family avoids introducing an incompatible additive package into the matrix.

Used correctly, the oil is what turns an ordinary porous metal blank into a component that lubricates itself for its whole service life. Selecting PE1152, TURBO T100, METADOP or PE1116 against the real speed, load and temperature profile is the single most effective way to get the design life the sintered bearing is capable of.