polyurethane bushings and petroleum based grease

[bigj480]

I am in the process of installing polyurethane bushings on my car and I have a grease question. The bushings didn't come with nearly enough grease, so I bought some "Sil-Glyse" grease from NAPA. Most of my front bushings were greased using this. I then found out that, although it contains some silicone, Sil-Glyde is primarily polypropylene glycol and polypropylene glycol is a petroleum product. Supposedly, one should not use petroleum based grease on polyurethane bushings.

So here are my questions:

Do petroleum based greases chemically "erode" Polyurethane as some have suggested?

If not, is there another reason that it would be a poor choice for this purpose?

I have the whole front end back together and torqued at this point, in your opinion, is it worth it to take everything back apart and re-grease using a silicone based grease?

I know that questions regarding poly bushings and grease have been asked here before, but I found no answer to the specific questions that I asked.

 

[rclint]

We use the polyurethane bushings at work with zero grease used on them, there may be some grease put on when installing to help fit them to the part, and trust me on this everything from soap to grease that cost $800 for a small tube is used.. just whatever is on hand I guess.

 

[tom slick]

polypropylene glycol has the same mild effect on cast polyurethane as water. on a scale of 1-4, 1 = little effect, 4 = severe effect, both are 2 as are most common automotive chemicals.

Petroleum oils are not an issue, in fact forms most are considered 1 or 2 on that scale, it's ethers, acids, and ketones that do the most harm.

I'd run it as is with no worries. Rubber bushings are the ones that would issues with petroleum products on them.

 

[bigj480]

Interesting, it seems that there is a widespread misunderstanding in automotive circles about this then, as it is parroted all the time. Perhaps Petroleum based grease will not last as long in bushings and that leads to premature wear and the misconception that its a chemical reaction. I don't know enough about the subject to say.

Thank both of you for the advice. If industry doesn't care what grease is used and the grease I have is no harsher on polyurethane than water, then I'm not worried about it. Worst case scenario, I end up with some squeaking and have to attempt to lube the bushings without disassembly.

 

[tom slick]

The only reason to lube poly bushings is to keep the squeaks down and dirt/water out.

Straight from an energy suspension rep

Quote:
Polyurethane being a synthetic is not effected by petroleum based greases. As where rubber (which is petroleum based) is. Our proprietary formula for our polyurethane is resistant to many chemicals that would normally have an adverse effect on OEM rubber components.

Silicone grease can be used without worries but Energy Suspension strongly recommends using our own Formula 5 grease for future installations and if that cannot be obtained than a "Quality" Marine formula grease is recommended.

I hope this answers some of your questions and doubts, feel free to ask us any other questions that may arise in the near future.
Jeff Bonnett
Energy Suspension

 

[bigj480]

I'm no longer worried about the grease I'm using, though the energy suspension rep does recommend a marine grease. Thank you for your service and thank you for taking the time to hunt down that quote, Tom.

 

[dailydriver]

I think E.S. suggests their 'Formula 5' because it is THE most tenacious, tacky, indissolvable and water resistant stuff made. (Besides making money on it, of course.

)

The only thing that might come close is the new Amsoil Off Road stuff, or some of the Schaeffers greases.