For thrust bearings as well as just about any bearing, I use Conoco Dynalife GC-LB, EP Lithium Complex grease. This came with the grease replacement tool "The Greaser" from Pete's Hobbies. Though it contains lithium, the MSDS sheet shows it's lubricant is petroleum based. So it should not be safe for rubber or plastic. Before I knew about the petroleum contact, I had used it on some rubber and plastic without any ill affects. But it still makes a litttle nervous to use it on
For rubber or plastic I used "plumber's grease". The stuff I have now is from Danco and comes in a 0.5oz tube. I did get some at Home Depot, but it had a definite petroleum smell and was not clear. The Danco stuff is clear and no odor.
For special occassions I break out my Tamiya friction damper grease used on thier 1/10th scale F1 chassis. This stuff is expensive and can be hard to find. But it did wonders for the friction strap on the collective in my DX7. I have a couple tubes left over my RC racing days.
I have tried the Tri-Flow synthetic grease. I found that it did not seem to hold up well and became very thin and sticky after use.