I know the actual green Simple Green isn’t recommended in aluminum, but the HD purple stuff is okay on Aluminum parts.
I just cleaned a couple of K&N air filters on a BMW X5 and was out of the cleaner solution and used some Shout It Out laundry detergent designed to get grease or spots off clothes. It worked great and I just rinsed them real good and blew them out with air and set in the Sun for a little bit. Sprayed some light oil on them. They looked alot better than the times I have used designated cleaner.
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