There are many threads covering this topic, the big question is what to do with the leftovers. I don't know the disposal procedure for the castrol stuff is, but given it's an engine degreaser, I'd have doubts that it's down the drain...
For something biodegradeable and cleans up with soap at worst and doesn't require rubber gloves, go for Simple Green. There are a few generics out there (one is called clean green). I'm almost thinking something like windex will work too, but haven't tried it yet. I've also steered clear of anything with Pine oil in it, figuring the oils may not be good on most materials.
Granted whatever you are left with after cleaning is an enamel soup that shouldn't be poured down the sink regardless. Fortunately, you don't necessarily have to. In simple green's case, it can be reused for a long time.
Get yourself some sealable jugs. I got about five 128oz jigs from the dollar store. There are many shapes and sizes for almost any conceivable part. When the parts are clean, seal the jugs and put them in a cabinet somewhere for next time. After some time, all the gunk sinks to the bottom and the liquid can, mostly, be poured off into another jug. I guess you could sieve it too.
Also get a cheap electric toothbrush. Let it do all the work for you on the tiny details. And you gotta have a green-scrubbie-sponge-thing for large area cleanup. Clean under slowly running water and drop the part back in the bucket if it needs some more time.
The castrol stuff is supposed to strip in a few hours. Simple green startes working in hours, but takes a day or so depending on how thick the paint is. On exceptionally tough thick paint, I left some resin parts in for a week. No damage to the parts.
I've heard hat EZ oven stuff is good, but haven't heard if it damages resin or vinyl parts. Don't know about castrol for those materials either.
