AO

The Zerex G-05 solves both issues.

worf928

I'm sure I can find an infected pustulant pimple on its OATy-butt somewhere.

I'm waiting for MK now. Have already figured out what to post.

jcorenman

Here you go... the last post has links to two previous threads.
https://rennlist.com/forums/928-foru...t-coolant.html

I think using distilled water is important, there's enough chemicals in coolant without adding more.

Which leads back to the OP's problem with the block drain: It's going to be hard to flush the block effectively without getting it out.

worf928

I replace a lot of block drain plugs. If they don't look almost perfect they're gone. They're a couple bucks each. It is important to use a new AL crush ring with a tiny dab of anti-seize and to do your best to torque the plug to spec - not a lot of space up there.

In this case my bet is that the last time no paste and/or no new crush ring was used and/or the plug is way too tight.

I have had success with removing crudy plugs with my special set of 'rounded-off' bolt sockets the likes of which you can get on the web etc.

However, if the threads in the block drain have been stripped then removing the old plug could lead to a bigger problem. Unfortunately I don't know a way to tell without opening the box.

If the block drain boogy man is too frightening, then I'd do one or two flushes with distilled water to at least dilute the stuff that's left in the side of the block that cannot be drained.

JWise

At one of the financial institutions I formerly worked for, we had a repo that came with that stuff as a factory fill. During the course of inspection when we got it back, I took off the radiator cap for a look. The passageways were largely blocked with a sludgelike substance, not the normal deposits you see. Dexcool will never see use in my 928. YMMV.

worf928

Wait. Not so fast LLama-Man. The Yellow-bottled Prestone 50/150 non-Dex-Cool stuff is also phosphate free. (From the other threads.)

Andre Hedrick

Mobile 1 or Amsoil

dr bob

The G05 stuff is not too dificult to find, so there's not much reason to worry yourself by using Prestone in your 928.

I've had varying results using Prestone in other cars. For instance, the 2004 4-Runner is supposed to use the Dex-Cool, according to the G05 bottle. Aluminum heads on a FE block. I was planning to use the G05 but stopped. I may just buy the Toyota stuff and sleep better. In my now-gone Explorer, I had a head gasket leak coolant externally after a year of Dex-Cool. Replaced the gaskets, no problems. No evidence of gum precipitate in that system, but it was low-dosed (25%) with Water Wetter.

The block drain bolts seem to like to get stuck for some reason. My solution has been to use a 6-pt socket on a 1/2" drive, long handle, and pull. Wrestling with 3/8" drive or 12-pt sockets is risky to the bolt and/or your hands. Similar to what Dave recommends, I added a little teflon past to the threads with new washers. Then you just need to use enought torque on the bolt to make sure it doesn't fall out, since the washer isn't doing the sealing any more. Do Not use a lockwasher, since this will damage the sealing surface on the block and doom future users who might depend on the washer doing the sealing. The teflon thread sealing paste is in the plumbing section at Home Depot. You can also use Hylomar or Yamabond/Hondabond paste. New bolts are always a good idea, especially if you've (or the PO...) stretched them, or torqued heavily on them to get them out.

worf928

A note to clarify: The Prestone 50/150 in the yellow bottle (that I use) is NOT Dex-Cool approved. It is also silicate, phosphate, and borate free. You CAN get Prestone 50/150 in a Dex-Cool formulation but it comes in a gray (IIRC) bottle and has the Dex-Cool logo on it.

Tom928

+1 for the Zerex-G05 - I use it on MY 81 and 84.

A local pro wrench tells me that Zerex-G05 is better for the older cars (late 70's to late 80's/early 90's).
When I mentioned Dexcool he said that's for mid 90's on applications.

Just my $0.02

Cheers,

dprantl

Just use Zerex-G05 and distilled water ONLY and you won't have a problem. I've run it in all my cars for years. Around here they sell it at Autozone, NAPA and Advance Auto Parts.

Dan
'91 928GT S/C 475hp/460lb.ft

Bill Ball

Who cares about phosphate and why?

worf928

Well... folks that worry about no phosphates not protecting against damage caused by water pump cavitation?

Or folks that don't know whether or not they're using distilled water?

OH.... for $hi+$ and grins (not for you BB):

928autobahndreamer

It looks like those using the Prestone Extended Life formulation are good. This is what I went with based on previous threads. I was able to find this at Walmat and double checked the bottle to make sure that it was the right stuff.

Please stop giving me heart attacks. I have a hard enough time keeping straight what I am supposed to be doing to take good care of my 928 without having to panic about something I thought I had figured out before.

toofast928

I found more "weep" leaks with Dex-Cool than Prestone.
Just changed out the Dex Cool.