Didn't have heavy buildup, but it did a poor job removing two years worth of engine bay deposits from my Silverado. I haven't used their heavier product, but if your bay hasn't been cleaned in awhile use that instead.
I covered my battery with a garbage bag, and sprayed the entire can, then used the low pressure rinse at my local DIY car wash after waiting 25 minutes. I was worried initially but everything ran fine, the belt didn't even squeak.

I was initially skeptical and nervous about cleaning my engine off but it was necessary because of all the grime and coolant that's been leaking onto the engine. This was my first time doing something like this and I was so nervous to turn on the engine lol it was that moment when you thought that it wouldn't turn on because you messed something up, but the product worked great and it really breaks up heavy dirt and grime. I highly recommed to buy each step to make the entire engine bay look spotless!

I've now used this on two motorcycle engines as well as my 2005 Civic engine. It works pretty well. It didn't leave the engines absolutely sparkling, but they are definitely much cleaner, and any oily residue is all gone. My Civic for example had a pretty significant oil leak that I fixed, so I used this to clean up after, and now I will easily be able to tell if it's still leaking oil or not. And my 2003 Honda Nighthawk is already in excellent shape, so this just got any grime off the engine and left it looking pretty close to new again.

Essentially it won't necessarily make your engine look better than it should, just clean.

I've been using this at the car wash. Before I spray any water on the engine, I spray the Foamy Engine Brite all over the entire engine (avoiding certain things like the alternator, though) so it's completely covered. I let that soak for 10-15 minutes. Then I start with soapy water from the pressure washer and finish with a thorough rinse. I've gotten confident with the motorcycle and just use the pressure washer at full blast, but I was more gentle under the hood of my car because I didn't want to force water somewhere it shouldn't go. I haven't had any issues doing it this way on any of the vehicles.

Do you want your engine clean? Do you want to impress people when you pop the hood?

I've tried every brand of engine cleaner that is readily available and only this "Foamy" version does the job for me.

One can of this foamy cleaner is not that expensive. Use the entire can to completely cover your engine with the foam. Give it time to loosen the crud. You can rinse with a slow stream of water or you can use a pressure washer. Take care to cover anything that is sensitive to water or your car will not start......or it will and it will run like crap.

Follow up by spraying a complete can of foaming tire shine/cleaner over your newly cleaned engine. Your engine will look as good or better than the day it rolled off the lot.

You're welcome.

This is good stuff to keep around to clean up a mess or just clean up accumulation over time. It works best if you warm up the motor before (but not too hot cause it can ignite). Let it sit on the warm motor a few min than carefully spray off your motor with a house. Repeat if necessary. Does a great job!