see what i mean lol, some people rate it some dont. i have had more no's than yes's though so i dont think i will bother trusting it prolly not worth the hassle.
i might just use the cheap oil idea, with one of them magnetic sumps then put in the decent stuff.
Want a FREE/ish magnetic sump plug, read on.
But a fastener, same as bolt but threaded all the way to suit your sump plug thread, say 3 " long, and a nut to fit, put nut on fastener all the way, now wraps 5-6 wraps of insulation tape on the fastener next to the nut.
Now file, grind, or thiose lucky enough lathe off the rest of the threads, so they gone but no further(not needed).
Now take off tape, unwind nut, noting how it will clean any iffy thread at the same time, can always run a die on it if you have it.
It's not magnetised I hear you shout, get some wire decent thick wire about 3 feet long, strip about 8" out of the centre of the length of wire, stanley knife etc is good here, wrap around the bolt(not threaded part), get some mug to hold each end of the wire onto a battery pos and neg for a few secs at a time, this will magnetise it.
CAUTION thw wire will get seriously hot, and WILL burn so take appropriate measures, you don't need to try and hold for a minute at a time, I find a total of around 20 secs is plenty, if not wanting to magnetise this way, use some jump leads and place the bolt in the circuit between your cars battery and lead that goes to that post, ie so the jump leads extend the circuit of the battery post to the battery connection terminal going to starter etc, obviously be careful not to cause shorts etc, any flow of lectrons will cause magnetism, start a few times it will be well done, won't even get hot, can easily pass the current and a lot more.
Use MILD STEEL ONLY for the bolt not chromed, anodised or SS.
tabetha