I'm certainly not an expert, but I think the general rule is to use lithium grease on metal and silicone grease on plastic.

I use a white light silicon based for both. I use a tooth pick to put it on the worm gears and parts , it does not take much and helps get it in the grooves:) . Yes IPA does clean the the worm very well.

TheMobRules wrote on 2024-01-21, 22:45:

[*]Silicone-based grease without PTFE

Fixed.

Silicone grease is the most stable, long term, and was rarely, if ever used by drive manufacturers. The PTFE additive makes it "gummy" for lack of a better term. You don't want it.

But you might want to pass over silicone grease in favour of some simple petroleum-based grease because it is difficult to get the correct consistency for silicone grease. You can experiment by adding silicone oil to silicone dielectric grease until you get something you're comfortable with, but there's no "rule" per se.

The Lithium additive that makes lithium grease white is also unecessary for your application.

Something like this is inexpensive and will last you a lifetime.

danieljm wrote on 2024-01-21, 23:43:

I'm certainly not an expert, but I think the general rule is to use lithium grease on metal and silicone grease on plastic.

This is correct.

White lithium grease is petroleum grease and is not plastic safe. (Like dissolves like).

PTFE is a pressure additive and thickener. It will not gum up over time. In other words, it will not progressively thicken.

Lots of misinformation in this thread.

A polyurea based grease is commonly used (the yellowish looking grease) by manufacturers for small electric motors and plastic gears. Also a good option. However, you'd have to buy it.

Edit: Also be warned that many automotive use silicone greases are actually petroleum based grease with some silicone added.

kingcake wrote on 2024-01-22, 04:19:

PTFE is a pressure additive and thickener. It will not gum up over time. In other words, it will not progressively thicken.

It will not gum up over time -- it is already "gummed up" -- that's what PTFE does, it gums up silicone grease. It doesn't solidify it, if that's what you mean, and when you say "thickens", what it actually does is it makes grease somewhat taffy-like for lack of a better term.

Use water based lubricant and remember to always use more than you think you need, and then some.

Jokes aside I go with silicone grease on everything because AFAIK it is safe on everything.

TheMobRules wrote on 2024-01-21, 22:45:

However there was quite a bit of old crusty gunk on both the worm shaft that moves the head and the metal rod that serves as a guide for the head assembly. So I cleaned those thoroughly with IPA but at this point I'm not sure what lubricant to use... If I try to look up online forums and guides, everyone seems to have their own opinion about it, and everyone seems to feel very strongly about their opinion being the only correct one.

Metal rods should be dry. If those bind you need to take them out (in most modern drives, including 5.25 ones, this can be done without causing head misalignment) and clean both the rods and the bushings in the sled. 90%+ IPA works well for this and is usually plastic safe (IPA itself is safe but light and time breaks it down and forms acetone, and anything less than 99.9% IPA will contain some trace amounts of sulfuric acid). With some patience you might be able to clean this area without disassembly but it's usually faster to just take the rods out and the results are better too due to better access to the bushings.

The bushings should be brass but some cheap drives can be just plastic on metal. If the bushings are so worn or scratched that they bind even clean you can consider lubrication - but keeping in mind the rods will now attract dust and gunk up again. The more dirt, the faster the bushings will degrade and even the rod can get worn out a bit (usually though it's made of really hard steel and is not easily damaged). So it's kinda last resort fix if there are no spare parts to swap - it seems to work well initially but will fail in time due to dust and/or the lubricant hardening.

The worm screw is best treated with plastic-safe lubricants. Some drives have metal parts sliding in the groove, some have plastic (at least part of it is plastic). Transparent silicone grease is best though as other said it can be a bit difficult to apply due to non-uniform consistency. Might be easier to do if it's warmed up a bit first.

Metal on metal, especially with iron or steel parts that can rust, I would use petroleum based grease. Reason being it tends to wick into metal pores better (due to some amount of lighter fractions present in it) and prevent rusting, and also having better adhesion to the surface. Polished surfaces, like the rods, don't really benefit from that however.

EDIT: Re binding rods, do not judge that when trying to insert the rod back into the bushings, those are very tight fit (and for a good reason). Once the rods are in place move the entire sled/head assembly - it should move pretty freely using a single finger. Only if the sled has hard time moving or there is spot that binds, and swapping or rotating the rods doesn't help, consider lubricating.

Thanks for the replies guys! I guess I'll go with silicone grease then... even though both the rod and the screw are metal on metal there are plastic parts nearby, so I won't risk using the white lithium grease. I wasn't aware that it's aggressive to plastic.

Still, it would be nice to find some service manual or something for these old drives with suggestions from the manufacturer!