When it comes to polyurethane, there is no such thing as too much grease.
Prothane Super Grease pre-lube
Do Prothane bushings squeak?
Have you ever been told that Prothane polyurethane bushings squeak? Can DST let you in on a secret? Polyurethane bushings can squeak, but there is a way to prevent squeaking. It's pretty obvious really. Just use Prothane's 19-1750 that comes with each kit to lube the parts properly when you install them.
OE rubber bushings might not squeak, but they do crack
With the OE rubber bushings, you don't have to worry about squeaking. There is a permanent bond between the metal housing and the rubber bushing, so there is no opportunity for them to squeak. Unfortunately that permanent bond, mixed with all of the tension the bushing is under, causes them to crack or split. As your suspension travels, the rubber bushing pivots in the center. Since the housing and bushing are attached there is no relief for the bushing, so it stretches in the middle and then rebounds back when the suspension returns to its normal position. Over time this causes the rubber to crack, and then you aren't going to care about squeaking. All you will care about is the faulty alignment, loud clunking and poor handling.
Polyurethane is a much firmer material for suspension bushings, and it can withstand the large amount of stress that bushings endure. Instead of the permanent bond like the rubber, you get a free floating design that gives you a huge boost in performance and bushing life span. But this free floating design also means there is no permanent bond, which opens up the opportunity of squeaking due to the friction between the polyurethane and the metal.
Prothane's Super Grease
By utilizing Prothane's own 19-1750 that is supplied with each bushing kit, you can have a great performing suspension without that annoying squeaking. Each Prothane kit comes with the minimum amount of grease required to install, and we also have some extra tubes in packages of three for pretty cheap with 19-1750. So you could pick up a few extra packets, just in case you spill some or need more during the install. When it comes to polyurethane, there is no such thing as too much grease.
This stuff is sticky...
Prothane's 19-1750 was designed specifically for their bushings, to prevent polyurethane from squeaking, so it really is the best option. This stuff is sticky, and I mean sticky. We at DST recommend that you wear latex gloves when applying the grease, because it is very tough to remove. If you think it would be difficult getting this stuff off of your hands, getting the grease off your bushings is even harder. Prothane's 19-1750 is a PTFE, water-proof Lube that clings to the polyurethane. Meaning it isn't coming off without a lot of soap and a ton of scrubbing. Not only is this grease waterproof, but it's also heat proof, making it an ideal suitor for Prothane's bushings. Coat it liberally, using as much grease as it takes to completely cover the bushing wherever there is poly touching metal.
Can I use any other type of grease?
If for some reason you don't want to use Prothane's 19-1750, you technically can use any grease you want, you aren't going to hurt the bushing. But the difference is longevity, not only of your bushings, but also your squeak free ride. We do not recommend using regular automotive petroleum grease as that grease washes out way too easy. Marine grade grease is the best alternative to use, because it is tacky and waterproof. But regardless of any alternatives, you shouldn't expect the same results as Prothane's option. This 19-1750 was made specifically for this polyurethane, ensuring a squeak free ride and a long lasting bushing.