How do YOU protect your transmission case from corrosion?, What coatings do you use? Options

[Dr Evil]

I am trying to finish my notes to accompany the rebuild video (notes will be free) and I am wanting to pick your collective brains for info on corrosion prevention for the mag alloy case. What do you do? The factory coating only lasted a few years and is long gone now. On most peoples cases, it is the oil that keeps it from corroding (IMG:style_emoticons/default/wink.gif)

[Richard Casto]

I should also mention that I was looking to go for "period correct" look/style (I also wanted it to be cost effective) with respect to a method to protect the transmission case. Back in the day Porsche used a chromate finish to provide temporary protection to the parts between the time they were machined and when they were assembled. Chromate finish provides decent, but not long term protection. So it was never intended to really protect the case. What Porsche did was spray the assembled case with a product named Tectyl which is a waxy coating. The CRC product above is similar to Tectyl.

If you are not looking for period specific or a low cost solution, then there are many newer coatings (particularly aerospace based) that can be used on magnesium and aluminum. However some of those may result in oddly colored finishes (such as green). You might be able to find someone willing to do another chromate conversion process on a case if you want to replicate the factory finish (particularly the brassy color the chromate finish gives). However most (all?) chromate conversion processes use hexavalent chromium which is nasty stuff. The movie Erin Brockovich is about people who were poisoned by hexavalent chromium. So the stuff is just about outlawed today and may be expensive to have done.

I have not put much thought into painting a case and if that is a good idea for the long term. However I know that many people do paint their cases.