- Discolored or foamy substance on dipstick. The oil collects moisture in colder ambient temperatures. You may notice that the dipstick will look like it has wierd discoloration. This has been discribed as foamy, milkshake, white crap, brown oil, etc... This is normal, and nothing of concern. If you want, you can pay a large chunk of money to make it go away, but there is no harm to it, so just ignore it.