So here is the update, along with a few questions.

I checked the coolant, and its green. What color is it supposed to be?

I went to jiffy lube for the transmission change, and they did indeed use the machine. For clarification, a guy in his mid-30s did the change, and he left the other 5 of his buddies in the oil changing bay to go do it. He was the specialist and seemed to know what he was doing (thank god, and it looks/smells MUCH better now. I stood 4 feet from him the ENTIRE time observing every move he made.)



The jiffy lube guy made a few notes to me while he was out there.

One, he said that despite my gauges telling him the temps were ok, the coolant was apparently "obviously boiling over." (he just about burned his face off with the billowing steam that came out when he opened it up). Does that sound normal? The coolant temps were reading about 210-215.


Two, he noticed that Firestone did not properly replace the cap on my brake fluid resovior. I promptly drove (40 yards) to firestone and BITCHED at their manager who promptly ordered in a complimentary GM part for me. He said that there should be absolutely no problem with the fluid and that it should not need a flush. Is he just ing me? He said that only oils would be a problem if they got into the resovior and that the fluid in there was hardly used in the first place. Someone please enlighten me?


Three, one of the guys at the Jiffy lube said that my maintenence schedule suggested I work on my rear diff. every 7500 miles. (I would assume this would mean changing the fluid?) If someone could shed some light on that subject as well it would be much appreciated.

Thanks guys!

 

I'll tell you what I do on my 90. I'm the second owner, when I got the car it had 8200 miles on the odo but it was 15 yrs old. Previous owner went by the book schedule so before I used it for the first summer I changed out:

coolant after flushing the system with just water and my schedule for this will be every two yrs. I use 1825-M GM coolant I buy from a dealer on-line. It's what came in the 90 C4's. It's a silicated coolant. I swapped T-stat & tank cap & all the hoses the first time and pulled the rad & cleaned out all the debris & made a screen to stop the debris in the future. Not a fun job so I made the screen...yes it's not pretty but r & r'ing the shroud isn't my idea of fun.

Trans, GM syncromesh fluid every 8 to 10 K miles. I have a zf6spd though.

Rear, used GM gear fluid + two bottles GM additive. I will also do this every 8 to 10K miles. Makes for easier check lists. It is easy to do if you have a suction tool & an old fashioned pump type oil can to use to refill.

Now I'm positive all the fluids that GM sells are synthetic and that 20K miles is proly a good bet or maybe three yrs...depends how you feel about it. My take is that I know every two yrs, mine is not a DD, I know that I changed what should be changed. I don't have to guess or remember what I did & didn't do...expensive & a waste of $, yes & no. Peace of mind that in theory I shoud not have a failure related to lube oil failling....priceless. JMHO.

I don't know what to tell you about the JL guy & the steam thing. I doubt that I would go anywhere near my cooling system unless my car was shut down for at least an hour and even then I would not expect things to be safe. The guys that are more knowledgeable about C4's should have something to say about that. All I know is that the C4 is a hot running car in b to b traffic. My gauges do not have degree gradations so I can't speak to what the JL tech said about the boiling over condition. I can only say my car w/the A/C on in b to b traffic stays in the upper third of the range, if I get any forward motion the gauge comes down to the mid point. On the highway it hardly gets above the mid point, A/C or no A/C. In b to b w/o A/C it will run higher on the gauge because the fans are not constantly running...the ECM has set points for both fans on & off temps, with the A/C on both fans are running all the time so there is more air drawn thru the rad.

Tom