What supercharger oil should I use in my AMR500?

AMR500 and AMR300 superchargers require a specialist oil. You cannot use regular gear oil or motor oil. 

Other copy-cat manufacturers recommend the use of AC Delco supercharger oil. However this is NOT the correct type of oil to use. That stuff is specifically designed for Eaton superchargers, and whilst it has 'supercharger' written on it, it is not actually suitable for Aisin superchargers.

The most common failure we come across when rebuilding superchargers is due to incorrect oil being used. This invariably results in brittle and cracked bearing cages. Most often the cages disintegrate when the bearings are removed, meaning that in most cases the bearing cages are being run at the brink of failure.

The AMR along with other Aisin blowers use non-hypoid gear sets. This means that regular gear oil is not appropriate. Regular gear oil is also far too thick to spin at 16,000 rpm and will churn and foam creating extra heat. EP80/90 is the most common type of oil recommended by those selling remanufactured AMR blowers. Great for tractor axles, not so much for superchargers.

Aisin blowers use a polymer bearing cage on the open rear bearings. Polymer bearing cages require a non-aggressive oil additives to be used, unlike those typically found in gear and motor oils. This is the reason that regular motor oils cannot be used. This is also another common recommendation by the Temu crowd.

This bring us to the AC Delco supercharger oil. Whilst it does not use aggressive additives, it is a Poly-Ester (POE) synthetic oil, which whilst being exceptionally good at higher operating temperatures, is unfortunately incompatible with polymer bearing cages. This is not an issue for Eaton blowers as they use steel bearing cages.

The reason for this incompatibility is the chemical rule: "like dissolves like." which means that the Poly-Ester synthetic oil triggers several distinct reactions with the polymer bearing cages:

Absorption and Swelling: Because both the oil and the polymer share polar characteristics, the resin cage acts like a microscopic sponge. The polymer chain absorbs the ester molecules. This causes the cage to swell, altering its physical dimensions. At 16,000 RPM, even a few microns of swelling disrupts the tight clearances around the rolling ball bearings, creating intense localised friction.

Plasticisation (Softening): The absorbed ester fluid acts as a plasticiser. It embeds itself between the polymer chains, increasing the free space between them and lowering the material’s Glass Transition Temperature (Tg). This causes the cage to soften, lose its structural rigidity, and warp or flex under high centrifugal forces.

Chemical Degradation (Hydrolysis Risk): Under heavy heat cycles and exposure to any atmospheric moisture pulled into the casing, polyol esters can undergo hydrolysis. This reaction reverses the chemical process that created the oil, forming organic acids that aggressively attack and break the molecular backbones of the polymer cage, causing it to become brittle and crack. This is the most common failure we see when we rebuild blowers that have been using the wrong oil. This is easy to spot as the right oil is a completely different colour.

So it's very important to run the correct oil in your supercharger. Recommendations given by your typical Temu blower sellers are plan wrong. And whilst you may think that the 'Supercharger oil' recommended or packaged up by those copycat sellers is the right stuff, it isn't. In fact, I can tell just by looking at a photo of it (it is the wrong colour)

The correct oil is just part of the information that you have access to as a Joe Blow customer, and is part of the many years of research and development that has been undertaken by a qualified engineer, that makes our products and support the best in the business.