Somewhere along the way, my front end got covered with tar. It was all over the underside of the pin area and front storage. I spent an hour going through every fluid in my rig and nothing worked. I was down to beer as the last candidate.
I have an aversion to any form of alcohol abuse, and using beer to clean with seemed beyond the pale of reasonable alcohol usage. I was about to give it up and open one for brunch at 9 (I'm in Oregon so it's OK) when I stumbled upon "Goof Off".
This is a "Goo Gone" knock off intended mostly for adhesive residues, etc. Anyway, I tried it on the grease and it was sweet. In the process I discovered it also takes off that black road grime you get in all your seams on the caulk.
I've never been able to get that stuff off, at least not easily. This stuff takes it off instantly with just a paper towel.
I got "Goof Off" at Home Depot. Buy some. You'll be a happy camper. I got dirt off that had been on the rig since I bought it. The bad news is that cleaning seams on my front end uncovered loads of seams where the caulk looked good but was badly separated from the skin. Pushing on it to clean it exposed lots of problems.
If the dirt is the only thing keeping the water out of your rig you might just want to skip the cleaning.
