: 1999 STS coolant questions

10-30-13, 08:49 PM
I brought my 1999 STS (105,000) in for its inspection and an oil change and asked the mechanic about getting a coolant flush. He didn't have the machine and when I picked it up told me it was low on coolant and I had a big leak at the water pump. The car sat for a few months before I got it and I new it was low on coolant. He quoted the job at $700-$800 and complained about how difficult the job was, but told me it's really common for that car. I never saw any fluid under the car and 100 miles later, the coolant level is just where it was when I got it back. He also filled it with green fluid. No over heating, great heat and gauge position. I've owned 3 caddys of this vintage and always had to add oil and coolant occasionally. Any thoughts?

10-30-13, 08:59 PM


A coolant flush is unnecessary.

WP leaks are not "common" on these cars.

WP replacement on a pre '06 Northstar requires a fairly inexpensive pump removal tool, but the job is actually quite simple. ('06+ require crossover removal - A LOT more work).

Your "mechanics" price is a bit more than double what it should cost you.

"Green" (universal) coolant is just fine.

Lots of good information on oil consumption in the Cadillac Technical Archives (black tab at the top of the page).

If you were adding coolant, there was a leak. Either external or internal.

10-30-13, 09:17 PM
Good thoughts. The price seemed way high after I checked out the repair on you tube. I chased some threads on here about dex cool. It seems the tablets and dex cool aren't required anymore, but for a few extra bucks I think I'll stick with oem. Thanks

10-30-13, 09:20 PM
You can use whatever coolant you'd like, as long as it's mixable with DEX-COOL. Nothing wrong with sticking with DEX.

However, I'd recommend not using the tabs. They're known to clog small coolant passages.

10-30-13, 09:54 PM
:yeah: I'll second that.

11-14-13, 03:52 PM
If your mechanic complains about how difficult a job is, I would find a new mechanic that actually looks forward to doing the job for you. My mechanic at Spearfish Cadillac is always happy to do the work needed: I think he loves his job. Also my mechanic can change my coolant in an hour, I do it every fall.