A friend showed up today while I was making battery tray brackets for the winter upgrade project, and as often happens when folks stop by, I got the "why aren't you using the creeper" question. I have two creepers (good ones) and have had half a dozen others, but they always seem to find there way to leaning on the wall, and I am back to using a scrap of carpet. It is not intentional or planned, it just happens.
The benefits of using a creeper are obvious, it has wheels to move you in and out, and a headrest if you need a nap.
I think, at least for me, the difference comes from two things, that are not 100% of the time, but often enough to prevent switching back and forth between carpet and creeper.
1. You have to get the vehicle a couple of inches higher to use a creeper and have the same amount of work space.
2. A lot of the under vehicle work I do entails tight bolts to loosen (that I can't get with the impact) and tighten, and things like drilling holes in the high strength frame parts that require a lot of force.
The logic of #1. is obvious, it is harder and you need better jacks and stands to do it.
#2 is tougher to define, but it seems that whenever I try to use the creeper, I wind up trying to drill a hole, loosen something, whatever, that requires a big sideways push, and zoom off I go rolling away on the creeper because I can't get a good push without rolling away. Usually, I leave a bunch of skin somewhere because the wrench or drill slipped when the creeper took off. On a piece of carpet, I am not strong enough to make myself slide.
So--what do you all do? creeper or carpet or switch between?