Correct PS fluid for BB 427/390

[Jerry S.]

Looking for advice on the correct PS fluid to use in my slow leaking 1966 BB. I have seen recommendations for use of GM #12345867 a.k.a. AC Delco 10-5044 but also suggestions that it would not be a good choice due to the excessive heat of the BB (and Arizona temperatures). Also wondering if the products like Prestone with leak stop would be a viable option? Was hoping to just add fluid to keep topped off but if I need to flush the system after determining how bad the leak is, I guess I'd go that route.

[Mark E.]

Re: Correct PS fluid for BB 427/390

Jerry,

This is a thoroughly discussed topic on the Forum. Search "power steering" or "power steering fluid" for your fill of advice about fluids and PS leaks. In a nutshell: any power steering fluid for GM vehicles will work; stay away from stop leak snake oils; expect the system to leak at least a bit; and never grease the zerk on the PS valve (doing so contributes to more leaking).

Below is a reply by Joe Lucia from one of these threads with his sound advice. Good luck.

"If you want to use an original formulation power steering fluid, use GM #19329448, aka ACDelco 10-5073. If you decide to use a partially synthetic power steering fluid (a fluid labeled "cold climate" but suitable for all climates) use GM #12345867, aka ACDelco 10-5044. For me, I use the 12345867.

By the way, after you install all new system components, flush the system, and begin using it on the road, in a few months you'll have another leak. Practically guaranteed."

[Jerry S.]

Re: Correct PS fluid for BB 427/390

Thanks Mark, I've looked at all the previous discussions on the Forum and was referencing Joe's article about ACDelco 10-5044. I was told this would not be a great choice for heat related reasons. Now, I'll trust replies on this site over all else but am hoping to get real time experience for what to use in my case. The ACDelco seems to be available on Amazon so just want to make a good decision so as not to harm any components.

[Mark E.]

Re: Correct PS fluid for BB 427/390

You should be okay. At some point we need to trust the engineers who formulate the fluid considered the temperature requirements.

I'm currently using Red Line synthetic which seems to work fine here in Texas. The GM/AC fluid should serve you well too.