Is there really any difference in deck wash, car wash or for that matter, dish washing liquid?

I definitely wouldn’t use dishwashing liquid; I’d use deck wash. I’m no expert, but I would guess that you don’t want something that lathers up a lot and is difficult to rinse. Maybe research ‘how to wash wood’.

Probably.
For example, my tabletop dishwashing machine uses commercial dishwashing liquid, which is primarily based on potassium- or sodium-hydroxide, either of which is quite corrosive.

The deck wash is like a bleach liquid. I pressure washed my deck last summer.

Is it the deck of a boat or a deck made from wood planks, like a veranda?

I’d use liquid soap on the car.

@sorry It’s a deck on the back of my house made of wood.

That sort of wash is different from dish soap.. or it should be. There should be something for the green that grows on the deck, so it has less foaming agent and a higher pH. You can even use a ‘stain lifter’ to remove the colour you put down last time, give it a light sand and re-stain and it will look like new. Dish soap and car wash is basically the same.

A good pressure wash works miracles.

Yes. YES.

Dishwashing soap will break down the wax on your car that protects the paint. If you like to wash your car a lot, it really is not good to use it on your car.

On a deck dish soap would be too bubbly, and on the deck you might need other chemicals. Deck washing sometimes does not need any chemical, just a pressure wash. I would pressure wash.

Maybe you can use Murphy’s oil soap? I am not sure, but if the deck is stained and sealed maybe that would work.

Actually, she’s asking about washing a wooden deck.

Yes there is. Being it is made of wood, IMHO, I would simply scrape it/sand it and re-stain/re-paint after.

I decided to get a guy to power wash it. I’ll stain it as soon as I can after he is finished.

@chyna: When I power washed my deck last summer, it got about three shades lighter. It looked great! Then I put Thompson’s Water Seal on it, and it looks really wonderful.

Same here. Like brand new decks.