There are good and bad with using these. You cannot use it too frequently as it has corrosive agents that will spoil your rubber seals.

In my previous 2 cars (Toyota and Honda), I used their recommended engine flush cause they always up sell you this product in SC. The Toyota one I used for over 12 years and engine has no problem. No seals issue except for the flywheel oil seal which is common.

As for the Honda, even better. After 8 years the engine is still very silent.

Is it due to the engine flush or is it due to consistent engine oil change? I wouldn't know.

Maybe do it every 2 times you change engine oil. I am doing this but so far only done once cause seldom drive during MCO.

I understand some people get issue (like leaks) after doing it for the first time on their old car. I am not sure if you can blame it on the engine flush cause the car itself already have issue. The engine flush only bring out the problem. So it is up to you to decide.

Read that some el-cheapo pomen/users use diesel to do engine flush. Not sure what kind of issues it can cause but could be some old recipe used since old times.

What about when user got a second hand car? Not sure what is the condition of the engine and want to clean it a bit without spending extra money doing overhaul. Engine cleaner is a product that has been recommended by nearly all car manufacturers. We are not talking about things like seafoam or voltage stabilizer or grounding cables or camber nut. These are things that car manufacturer does not introduce for a reason. But nearly all car manufacturers does have their own brand of engine cleaner and recommend them as well. If you say, ya they are useless then do you believe in camber nut? Nearly all car manufacturers does not comes with camber nut. It's not due to cost because it is only few ringgit per nut. Also, they will never recommend you do camber nut if you tell them your alignment is off.

I am going to do something like this.

- pour in engine flush into old oil and let is run for 15 min. Then drain the oil
- pour in cheap fully synthetic oil (Bold) and use the car for 1 week
- drain cheap oil and put in new Shell synthetic oil. And new oil filter.

LOL...a bit more work but something I am experimenting...

Thanks for the suggestions. Will look into those suggested oil. For now, I am going to use same viscosity 0w20 fully synthetic Bold or Mizu oil as the cheap oil.

It's not as bad as you think. I have had my old car send to SC for 8 years. Each time they will do the engine flush. Engine was still quiet the day I sold it. First buyer saw the car and bought immediately.

What about your horror story in using engine flush? Mind sharing?

It's exactly Honda. And they always ask if want to do the flushing. Maybe new SOP they don't do anymore but that time they will happily do for you.

Changing engine oil seals means top overhaul already. By that time no need to flush..already open up the top engine can do cleaning already.

You have 2 ways of approaching this.

cheap and safe way - using good full synthetic engine oil with good cleaning additives. Use it for 1 week and try going into highway do some highspeed run within speed limit. Flush out the oil and see the oil condition. If it's dirty then do another round.

cheap and potentially harmful (though I don't think it's that harmful like "don't do drugs") - that is using engine flush. But do it sparingly. Flush with the old oil in it. Run the engine for 5 minutes. Then flush out the old oil and put in new oil. Run the oil for 15 min then flush OR run it for 1 week then change to another new oil. If you see the oil still dirty then can try changing another time after 1 week. But remember to use engine flush only once. If that solve your sludge problem then you are good but know that it won't be 100%. Clean enough is what you want.

more proper way and expensive - you can try the above method first but if you are not comfortable using engine flush with all the horror stories depicted here, you can straightaway do this. Do top overhaul to clean up the sludge. If it's bad case then you might need to do full overhaul. The price depending on the car and how bad is the engine condition.

Good information. The EO flushing method like I said drive for 1 week at least then flush out the oil and see the condition. Also some highway runs too if possible. Or drive like normal if your daily drive have highways. This will allow you to see the engine condition without taking out the cover. Repeat as needed. If the engine oil is dirty then change oil more often until you are satisfied with the result. By that time, if all is good, back to normal oil changing interval. When it already have lots of carbon build-up, normal interval with good quality oil will not help already. Need it change oil more often. Unless you want to try Royal Purple oil.