I'd avoid both, or any combination of both in applications that might be close to rubber hoses or fittings. Both hydraulic power steering fluid and acetone will attack these in short order. Good ultra-light sewing machine oil will do an excellent job in the absence of any real penetrating oil. Similarly, bike chain oil called Pro-lube is a first class alternative, being super thin.
As Doc says, Penetrene is good although I've never bought it, but used some provided by a third party on some jobs. I've used Inox on everything since it came out. It's colourless, non-staining, non-toxic, non-sticky, non-gumming, disperses water, and is non-reactive to rubber and neoprene. I've used it on my plane, boat, firearms and cars and around the house with equal efficacy and no adverse effects.
There is an excellent product called G-96 available from gun shops that is used to lubricate and protect the delicate mechanisms in guns and the metal surfaces. It's really space-age / US military developed stuff, though I tend to use it as a lube / protectant rather than as a penetrating oil, but it would do the job well.
Unless I'm really stuck for options, I won't touch "Toolkit in a Can", WD-40, DWF or any of the related products now, as they all have a similar base and all get gummy after the solvents evaporate to leave the oil base.
Last edited by Doug_MPS6; 23-05-2010 at 12:09 PM.
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