About 6 months ago (give or take a few days) I put white lithium grease that contains petroleum oil on a little over half a piston head with the o-ring on. I put it on at the beginning of the summer and planned to take it off at the end of the summer, but I sort of forgot about it until a few days ago.
Petroleum oil is supposed to degrade o-rings over time, and when I ordered the white lithium grease I didn't know it contained the petroleum. I'm not sure how long it should take the petroleum to start to affect the o-ring, but after 6 months (half year for those who are bad at math), it doesn't seem to have done anything.
I took the o-ring off figuring if the petroleum oil did anything to it I'd be able to see a difference without needing the marks i put on the piston. After I cleaned it I couldn't see any difference in any part of the o-ring. It feels slightly dry but that's what happens when you leave it in your basement for half a year without touching it. it feels like it dried out evenly, but they're are no cracks and I can still flex it with no problems. I'll probably use Cheese Man's "maintaining your bucking" guide in the others section to try to restore it, because it's still a perfectly good o-ring.
I didn't think it would affect the sorbo rubber thing on top, and sure enough, I can't notice a difference. I took the close up of it with the marking line right at the center of the picture. I forget whether the right or the left was the greased side in the photo, but it doesn't matter because there's no difference between them. I did mark with a sharpie which is the greased side on the side of the piston though.
So at least in white lithium grease, it doesn't look like the petroleum oil will do anything to your o-rings in a 6 month period. Maybe it takes several years, but at that point, you might be replacing the o-rings due to dryness anyway. I performed this test on a crappy piston which I'm never going to use again anyway, so if you guys think I didn't leave it long enough, or if i should have replaced the grease on a regular basis, I can always put the grease back on. Well on the piston I can at least. I didn't mark on the o-ring which side was greased or not.
P.S. My new camera has a macro setting
I love new toys.
Petroleum oil is supposed to degrade o-rings over time, and when I ordered the white lithium grease I didn't know it contained the petroleum. I'm not sure how long it should take the petroleum to start to affect the o-ring, but after 6 months (half year for those who are bad at math), it doesn't seem to have done anything.
I took the o-ring off figuring if the petroleum oil did anything to it I'd be able to see a difference without needing the marks i put on the piston. After I cleaned it I couldn't see any difference in any part of the o-ring. It feels slightly dry but that's what happens when you leave it in your basement for half a year without touching it. it feels like it dried out evenly, but they're are no cracks and I can still flex it with no problems. I'll probably use Cheese Man's "maintaining your bucking" guide in the others section to try to restore it, because it's still a perfectly good o-ring.
I didn't think it would affect the sorbo rubber thing on top, and sure enough, I can't notice a difference. I took the close up of it with the marking line right at the center of the picture. I forget whether the right or the left was the greased side in the photo, but it doesn't matter because there's no difference between them. I did mark with a sharpie which is the greased side on the side of the piston though.
So at least in white lithium grease, it doesn't look like the petroleum oil will do anything to your o-rings in a 6 month period. Maybe it takes several years, but at that point, you might be replacing the o-rings due to dryness anyway. I performed this test on a crappy piston which I'm never going to use again anyway, so if you guys think I didn't leave it long enough, or if i should have replaced the grease on a regular basis, I can always put the grease back on. Well on the piston I can at least. I didn't mark on the o-ring which side was greased or not.
P.S. My new camera has a macro setting
I love new toys.
