Use of lotion and oil
Among couples who enjoy whole body "slippery" sensation, there are those who love oil while others may prefer lotion.
By "lotion", I mean lubricant jelly for love. There are lubricant specially for genital area and also other lubs for entire body.
Personally, we often use the oil for whole body sensation. Jerry give a little too much lubrication that sometime it feels unnatural. With oil, even though it is slippery, there is "a feeling of body contact".
But with jelly, it's so slippery that it feels something different than holding human being.
(as if holding a dolphin...)
Of course, although it's a matter of personal preference and not that important, for adequate lubrication and soft smoothing of skin, I like the blend of grapeseed oil and baby oil.
Those massage oils for aromatherapy are good for your beauty and health, too.
As for the lotion, I like "Pepe" brand in Japan.
You may try different kind of lotion by ordering a sampler kit at "Blowfish" store on the net.
Whether rotor, dildo, or vibrator, they may be recommended by sex counselor for assisting women who have difficulty in attaining orgasm since these helper tools are effective.
(* Some doctors point out that too much use of vibrator for masturbation may result in frigidity even for women who weren't at the beginning.)
But we put "interdiction" against the use of these tools for actual "sexual union of man and woman" at Mumyouan. The biggest reason for it is these tools spoil the mood and they are bothersome. Further, the use of tools does not help at all, physically and mentally, in mastering sexual maturity and endurance. If you depend of tools, the true level of sexual technique will go down more or less inevitably.
Although such opinion as "There is nothing wrong with the tools for playful couples." is quite valid, it is much better if man and woman take care of each other mutually with their "bodies" and develop endurance and depth of orgasm by breathing methods and other training.
Also, since silicone and plastic do not have electric conductivity, they lack the important factor of bio-electric exchange between man and woman for natural orgasm. I have made a dildo with small electric voltage at the tip and asked my partner to try it. It was just a Hong-Kong flower (poor imitation).
We have tried rotor, as well. But dropped soon because it wasn't fun.
In our case, we experience "multiple orgasm" with "ejaculating inside" but "without barrier".
Also it is normal and natural to attain "simultaneous orgasm" and "fainting".
For us, simply there is no "necessity" for these tools any more.