Originally Posted by Pikey Dave
So that'll be a no then��
Lions led by donkeys
Not necessarily as I don't know the correct answer but having more knowledge of the effects of these cleaners can help you determine if needed or not and which one to choose.
I don't know what the formula is for Rydlyme and other similar products but they could have added a cocktail of different stuff that will clean out your engine properly while at the same time protect the motor. Maybe they're using organic acids which will explain the high price.
Citric acid in low levels and short time spans could be fine but it can most definitely corrode the metals in your engine if not done correctly. The cleaners with citric acid with the right additives can be used more heavily than just citric acid. We also don't know what are the metals are in the engine exposed to the cleaners. Remember that good aluminum has added metals inside it (zinc-magnesium, copper, scandium) to make them stronger and those metals are the concern.
This type of cleaner is actually a huge business in other massive industries like the food industry so there are companies that are fully dedicated to coming up with formulas to cleaning out equipment and scaling without damaging it.
Another thing to think about while using one of these cleaners in your engine. In the unfortunate environment we live and boating in is that there's oil in the sea water especially in harbors, these attach and coat the engine on the outside and inside. The cleaners, like citric acid does not do well cleaning the meta scalingl with oils coating them. It's always best to remove the oily film prior to using your expensive descaling cleaners. Maybe flush the engine with some dishwashing soap first to help remove the oils. It's just an idea. I know I must use a degreaser before using a acid wash to remove corrosion on greasy used tools and parts.
I will say there is a good purpose for these cleaners and descales like Rydlyme. For instance when you buy a used engine and you suspect the previous owner did not flush the engine properly. Also, just flushing it with fresh water will not take care of everything. If the water in the engine is exposed to hot temperatures then you will get scaling deposits just like a hot water heater collects deposits. All the fresh water flushing will not remove or dissolve heat-hardened scaling.