How about a 95 GM LT1?

[kevm14]

I've got a 95 Cadillac Fleetwood with the iron head LT1 (Caprice/Impala SS/Roadmaster) and while the cooling system performance is excellent (how about 195°F at 85mph with the A/C blasting in upper 90°F ambient temps?), I broke the radiator trying to replace the oil cooler lines. So I have the new radiator and I would like to flush the system. I have had good luck flushing with a garden hose, forward, reverse, engine on, engine off, pull the thermostat, etc, and I always use distilled water when I am done. I understand I may have block drains on either side (something other than the knock sensors I assume).

Anyway, I already insist on GC oil for my GM stuff (two small blocks, an L05 and this LT1, and a 3100 V6 - they all love GC, as did my LT1 Camaro when I had it), so I was wondering if I should be as picky for coolant. I just now found out that the all-makes stuff (specifically Supertech and Prestone) are very, very similar to Dexcool. Being a 95, my Fleetwood did not get Dexcool from GM, but it may have had Dexcool added somewhere down the line. Seems like I saw a reddish color come out. Some of that may have been rust, as I added RMI-25 a couple weeks ago, which by the way, I heard does not get along great with Dexcool. When I replaced the thermostat a couple weeks ago, I added a little 50/50 (all makes I believe) to top it off. Car has only 73k.

Seems like there are a lot of variables to juggle. I don't know for sure what's in there now. I have a gallon or two of Supertech all makes on hand, but my local Napa, which is very close by, seems to carry all 3 Zerex formulations, not including something proclaiming FLEET on it. Assuming I am sold on NOT running the all-makes stuff (any opinions?), how would I decide between regular Zerex green and G-05? What say everyone? It seems like the same folks that say "all makes" is great stuff also curse Dexcool, so if they are that similar, I can't trust the opinions of those people.

 

[daman]

Zerex G-05,have that in my GM's....

 

[Buffman]

I've had and used the regular Prestone Green Stuff with no problems. Get that car tuned and it can run cooler (turn the fans on a little lower

Matt

 

[kevm14]

Hmm, no votes for the regular green Zerex.

Matt, I have gone through and tuned all of that typical stuff myself. The fan temps are down to normal now, and I've done a bunch of trans tuning, as well. I put a brand new stock stat in (was running at 220 on the highway before that), so 195 means the system is working pretty efficiently. I just want it to continue to do so.

Still not sure what I am going to do...

 

[doitmyself]

Quote:
Assuming I am sold on NOT running the all-makes stuff (any opinions?), how would I decide between regular Zerex green and G-05?


I too don't like the Universal, fits-all coolants....I don't understand how they can cover both OAT and HOAT chemistries.

I'm not sure how you will decide, but here is how I would decide. I would confirm what the OEM coolant was, then install whatever is most similar to it. Case closed, worries over. No one can PROVE whether conventional or G05 is best. Both are great, why lose sleep over it. Everyone keeps forgetting that today's conventional coolant is unlike the old Prestone. It is low silicate and can last 5 years/100,000 (I like 3 yrs./60K).

IF your system, contains copper/brass components, then conventional coolant "might" protect it slightly better as stated in this excellent article: http://www.gates.com/brochure.cfm?brochure=2822&location_id=2877

Both the Zerex and Texaco/Havoline sites recommend the conventional. I imagine the G05 will work great too (been using over 20 yrs. in my John Deeres). I just don't want to spend time pondering about it. Just my way of thinking.

Because you don't know what's in there now. Flush it well and finish up with distilled water and coolant.

Good luck.

 

[kevm14]

I ended up buying the Zerex regular green stuff, which is what they recommend and seems to match what GM spec'd for this car in 95. I flushed very thoroughly. I wasn't able to get the knock sensors out so I couldn't drain the block. I don't really know how much water is in there now, so I'll have to add extra coolant and I guess before next winter, double check that the freezing point is low enough.

 

[Buffman]

be careful removing those knock sensors. They do require a very specific tq for tightening. Too much and they'll pick up a lot of false knocking.

 

[kevm14]

Well everything's together. Aside from thinking I killed my opti (long, bad day...), things seem normal. Except now the coolant temps are running about 10° higher than before. Instead of 195 on the highway it's more like 205-207. I assume it has nothing to do with the Zerex. It better not be the Napa radiator. I bled and bled but maybe there's air in there still...

 

[JohnBrowning]

Zerex G-05 would get my vote as well since it is avaialble and well tested.

 

[gradymotorco]

In my experience, if your vehicle came from the factory with Green coolant, stick with it. The only drawback I know of with it, is the short change interval, but otherwise, it will do fine.

Dave

 

[Buffman]

Originally Posted By: kevm14
Well everything's together. Aside from thinking I killed my opti (long, bad day...), things seem normal. Except now the coolant temps are running about 10° higher than before. Instead of 195 on the highway it's more like 205-207. I assume it has nothing to do with the Zerex. It better not be the Napa radiator. I bled and bled but maybe there's air in there still...


it sure would be nice if the [censored] thing wasn't under the waterpump or if it was waterproof.

 

[kevm14]

Well my opti is ok. Back to the temp thing. Why is it running so much warmer now? The thermostat is very recent and cured a problem where it was runnign in the 220s. It went to 195 under almost any condition where the car is either moving or the primary fan is on. I saw 207 on the highway last night after bleeding AGAIN, and I turned the A/C off and saw 205. At a light, I saw 209 or even 211 just as I come off the line. Ambient temps were under 80°F. That is terrible. That was with the A/C and primary fan on. Before it would have been 195 to 197, even in mid to upper 90°F ambient temps.

I did think of ONE variable. I added RMI-25 before I changed my stat and most of the mix obviously remained in the system (I didn't flush or drain at that time). I have purchased another bottle and it should arrive thursday. I know RMI-25 has many characteristics, one of which is being a surfactant (water wetter). Is it possible? If that doesn't fix it, what do I do? Yell at Napa? Get the end tank repaired at some radiator shop on the old rad and put it back in? I just don't know...