I spray all of the metallic parts that are exposed, I do the diff, its bolts, suspension bolts, inside wheel wells around suspension posts, bodywork through bolts, engine parts made from alloy etc etc. I do the front of the engine all exposed alloy, oil cooler >>> make sure you don't get it on the belts, but if you do it will eventually clear!!! common sense...
I normally high pressure hose the underside down and let it dry, then spray as much as I can reach, i put it on a rag and do the brake callipers, but away from the disc's, sound boring now, but my engine compartments even after 80k miles look brand new. I am not saying that this is a panacea to prevent everything, but I don't have sad looking rusted bolts or threads all over the place. Yes dirt can attach itself (but that takes along time) but when I hose the car down (even the engine bay or steam clean) it all comes back to new and then I just respray....It prevents water incursion to the electronics,It does not damage paint work, it is used by the military and on aircraft for the same reason
If you read the right ups on the products then you can make your own judgements!!! I am sure you will be able to find suitable alternatives!!!
Feel like I am doing an ad Lol
Always said I would go back to a 6 series
Last edited by 645/333; 12-02-2012 at 10:55 AM.