Yes run a proven ps fluid like redline synthetic. This is what I use and I began using it in road racing to eliminate foaming and boil over. Boats don't even come close to taxing a ps fluid like road racing can.

I run strictly autozone brand dexron trans fluid in my steering. Because its cheap and so am i. I ran all last year with no ps cooler. I did replace the cooler this year. Either way, never had an issue. Latham full hydraulic system.

Just addressing the 1 st couple post back in this thread, #1. 500 F in any marine engine compartment NO way - VAPOR lock city on that one , interior components melting, blistering paint, melting of all plastic parts and so on, along with running problems and battery issues from that extreme temps.

Next mercruiser has a Service Bulletin to dealers and boat manufacturers about engine compartment temps and do want any above 178 F. If the temp become higher than 176 F when running or even after shut down, fuel and other problems can exist. Mercruiser has studied this one and I know for a fact they did many many years ago..

If I read those temps wrong at 500 F in the first couple of posts never mind my post. Carry on.

Have to add just went back re read the post yep says 500 F degrees how I am taking it. Has anyone ever work on a marine engine after shut down or while running the engine and having the engine and or the compartment temps at 500 degrees. Hmmm that would mean going to the burn center for 3 degree burns all over your body.

im not saying that the person that said 500 deg engine space is full of chit but i will say he is very wrong.200 max maybe,500,not a chance!

Well I will say it is so far and wayyyyy off base. The engine would never run nor restart with 500 F temps holding for any length of time in a engine compartment.

next here is the jist and there is more from Merc and Volvo and OMC and Yamaha thru out the past years about engine compartment temps, vapor lock, carbs sucking down heated air and so on. .

Anyways here is Merc SB and Merc came out with more SB's in 97. 99 and 2001 about temps, engine compartment temps, fuel temps and vapor lock issues. I can not post the links from the OEM's but found this to post. It is 100 % the same SB's I get from the OEM thru out the years.

Like I said came out years ago (1995) to all Merc dealers and all boat builders.

Link below read it.

www.boatfix.com/merc/bullet/95/95_12.PDF

Still not completely relevant to actual ps fluid temps. Without readings in different applications, we are merely guessing. Good info nevertheless and thanks for the link BUP. You are quite the knowledgable fellow.

I'm running Dex 3 ATF. Don't even remember what brand I got.
First time I changed or even added to it was a couple years ago. That was only because I had a small leak at the connection to the high pressure side of the PS pump.

500 degrees? 600 Degrees? Gasoline ignites at 495 degrees F with no spark or flame

And I believe paper at Fahrenheit 451, lol.