Originally Posted by Strife

If you have an earlier than 1986 SL, you should check the front of the fender above the headlight pockets. I am going through my 85 380 and rustproofing it additionally for the winter as well as touching up some stuff. I kid you not, I pulled about 3/4 LB of wet, nasty dirt from the LH side and about 1/2 LB from the RH side in this area. It's a lot harder to get at the RH side because the vacuum resevoir is in the way. After doing this and letting it dry, I POR-15'd this area and while that was drying overcoated it with rubberized undercoat.The RH would have been much easier with the vacuum reservoir out of the way but it's held in with screws and not studs and it would take removing the water bottles and maybe 3 hands to remove it.

If you've ever seen a rusty SL with rust above the aluminum eyebrow trim, this is how it got that way. 86+ cars are fairly immune to this because of the plastic wheelwell liners. I got a set of these locally from a car being stripped, but they aren't that easy to install, because the studs to mount them aren't there and blind-drilling into the inside fender is NOT RECOMMENDED (I'd have to basically remove everything mounted on both sides before starting on this).