Nylon bearings?

Lubrication is likely to be a short term solution at best. I'd probably try some polyurea (bicycle) grease since I happen to have some around.

But if nylon bearings are sufficiently worn to flap around and make a noise, it's time to replace 'em. Just check to see that it's not something else generating the noise.

Ask the manufacturer? Read the manual? Virtually all power equipment manuals are online these days.

CWM

donh spake thus:

Oil won't harm nylon, which is impervious to most petrochemicals (at least those found around the house).

It might seem like a wild and crazy idea but have you considered reading the manual or contacting the manufacturer? Surely either of those would yield better information than strangers who have no idea what sort of mower you are using.

Use Lubriplates Aero grease. It's compatible with plastic and has good low temperature qualities.

Below is a guide to chemical compatibility for many materials:

Nylon is compatibile with almost all oils.

Just for kicks I selected aluminum and petroleum. It has a D rating - Severe effect, not recommended for any use. What is the reason behind this?

Aluminum block car engines and pistons? Huh?

By "petroleum" I think they mean crude oil, which can contain stuff that corrodes aluminum.

If you do the same check on "oils:mineral" (which is what ordinary petroleum lubricants are), it comes up A.

Aerosol grease would be easy. Most grease and oil tend to attract and hold dirt/dust/scuzz. I use a Teflon filled anti seize on similar things and have been quite pleased. Here are some examples:

Yes, replacement. Typically you replace such bearings when they act as you describe.