I just asked Garry Dean, The provider of the vast majority of my detailing products, what he'd use and this is what he said:
Do you have any
Tigers Blood he can try? (I'm sorry but I don't). it's a very powerful degreasing cleaner. It is for the heaviest of duties. Engines and the such. TB is super strong at 1:3 dilution. Tell your friend that if he should want to order a bottle of TB, to leave a message saying I said I'd also include some IPC (
Infinite Purpose Cleaner, another of his products) to see if that gives him the product he needs.
I hope this helps you!
BTW, he's running a Thanksgiving promo 25% off and free shipping for orders over $79.00 Use promo code "thanks25" at checkout (just in case).
Edit: Typo